Non-transmission surface liquid film multi-parameter synchronous imaging device based on absorption spectrum and measuring method

Abstract

The invention discloses a non-transmission surface liquid film multi-parameter synchronous imaging device based on an absorption spectrum and a measuring method. The imaging device comprises a laser emitting unit; the laser coupling unit is connected with the laser emitting unit; the laser attenuation unit is connected with the laser coupling unit; the laser diffusion unit is arranged on a light beam transmission path of the laser attenuation unit and is used for diffusing the diameter of the coupled light beam to an incident light beam with a preset size; the non-transmission flat plate is used for bearing a liquid film to be detected; the laser splitting unit is arranged at a position through which the incident light beam and the reflected light beam pass, and can enable the reflected light beam to penetrate to form a transmitted light beam; the imaging unit is used for receiving the transmission light beam and converting the transmission light beam into a grayscale image; and the computer is connected with the imaging unit and is used for receiving the grayscale image transmitted by the imaging unit and processing a two-dimensional distribution image of the liquid film parameters. The device can solve the two-dimensional distribution information of at least one liquid film parameter with high precision.

Description

Technical Field

[0001] The invention relates to the field of thermal physics and energy power measurement and diagnosis, and in particular to a non-transmission surface liquid film multi-parameter synchronous imaging device and a measurement method based on absorption spectroscopy. Background Art

[0002] Liquid film formation is widely present in various industrial processes, such as the formation of oil film on the wall of the intake manifold of automobile engines, the formation of fine water mist liquid film on the wall in efficient and clean fire extinguishing technology, and the formation of liquid film in the horizontal tube falling film evaporator in seawater desalination. Quantitative analysis of the two-dimensional distribution of parameters such as liquid film thickness and temperature can not only better understand the nature of complex physical processes such as liquid film formation, flow and evaporation, but also provide scientific basis and theoretical guidance for the optimization of various industrial processes involved.

[0003] In various industrial processes, liquid films are usually formed on non-transmissive solid surfaces (such as metals). At present, most of the measurement methods for liquid films on non-transmissive solid surfaces can only achieve single-point measurement, and the measurement range is limited. For example, when using ultrasound to measure the thickness of liquid films, the measurement area is only the size of the ultrasonic probe. When using traditional absorption spectroscopy to measure liquid films on non-transmissive surfaces, the laser is incident on the liquid film at a certain angle, and the detector receives the reflected light intensity signal after absorption by the liquid film. This method can only obtain the liquid film information of the path passed by the laser. The light intensity signal is weak, and the optical propagation characteristics of different surfaces are relatively complex. The liquid film parameter information obtained by single-point measurement is limited, and the parameter distribution of the entire liquid film cannot be analyzed. Therefore, it is an urgent problem to synchronously obtain the multi-parameter two-dimensional distribution information of the liquid film with high precision, which is not only conducive to revealing the heat transfer mechanism of the liquid film and effectively improving the heat transfer performance of industrial equipment, but also can provide theoretical guidance for other falling film flow process research involved in the fields of energy, chemical industry and medicine. Summary of the invention

[0004] In order to overcome the defects in the prior art, an embodiment of the present invention provides a non-transmissive surface liquid film parameter imaging device and a measurement method based on absorption spectroscopy, which can solve the two-dimensional distribution information of at least one liquid film parameter with high precision.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention discloses a non-transmission surface liquid film parameter imaging device based on absorption spectroscopy, comprising:

[0007] A laser emitting unit, wherein the laser emitting unit can provide at least two laser beams of different wavelengths;

[0008] A laser coupling unit, connected to the laser emitting unit, and used to couple the laser beams of different wavelengths emitted by the laser emitting unit into a coupled beam;

[0009] A laser attenuation unit, connected to the laser coupling unit, and used to reduce the laser intensity of the coupled light beam;

[0010] A laser diffusion unit, connected to the laser attenuation unit, for diffusing the diameter of the coupled light beam to an incident light beam of a preset size;

[0011] A non-transmitting flat plate, used for carrying the liquid film to be measured and reflecting the incident light beam into a reflected light beam;

[0012] A laser beam splitting unit is arranged at a position where both the incident light beam and the reflected light beam pass through, and is used to reflect the incident light beam onto the non-transmitting plate and enable the reflected light beam to penetrate to form a transmitted light beam;

[0013] An imaging unit, used for receiving the transmitted light beam and converting it into a grayscale image;

[0014] The computer is connected to the imaging unit and is used for receiving the grayscale image transmitted by the imaging unit and processing it to obtain a two-dimensional distribution image of the liquid film parameters.

[0015] The non-transmitting surface liquid film parameter imaging device based on absorption spectroscopy of the present application establishes at least one liquid film parameter inversion model based on the Beer-Lambert law. By analyzing the collected grayscale image, the relationship between the grayscale value and the liquid film parameter to be measured (such as thickness, temperature, concentration, etc.) is constructed, the specific value of the liquid film parameter to be measured at each pixel point is calculated, and a two-dimensional distribution image of each liquid film parameter to be measured is drawn, thereby achieving high-precision imaging of the liquid film parameters on the non-transmitting surface.

[0016] Furthermore, the laser emitting unit includes a laser controller and at least two semiconductor lasers connected to the laser controller. The number of the semiconductor lasers can be determined according to the number of liquid film parameters that need to be solved. For example, when solving the two-dimensional distribution image of the liquid film temperature, two semiconductor lasers capable of emitting different wavelengths can be set in the device. When it is necessary to synchronously solve the two-dimensional distribution images of the liquid film temperature and the liquid film thickness, three semiconductor lasers capable of emitting different wavelengths can be set in the device.

[0017] Furthermore, the laser coupling unit includes a wavelength division multiplexer, which is connected to the semiconductor laser via an optical fiber and is used to couple multiple laser beams of different wavelengths emitted by the laser emitting unit into one optical fiber.

[0018] Furthermore, the laser attenuation unit includes a first attenuation unit, a collimating lens, and a second attenuation unit that are sequentially arranged. The first attenuation unit is an optical fiber attenuator, one end of which is connected to the laser coupling unit via an optical fiber, and the other end of which is connected to the collimating lens via a single-mode optical fiber. The first attenuation unit is used to attenuate the laser intensity of the light beam emitted from the laser coupling unit. The second attenuation unit is a (near infrared) NIR neutral density filter. The second attenuation unit is arranged on the light path emitted by the collimating lens. The second attenuation unit is used to further attenuate the laser intensity of the light beam emitted from the collimating lens.

[0019] Furthermore, the laser diffusion unit is arranged on the optical path of the light beam emitted by the second attenuation unit. The laser diffusion unit is used to widen the diameter of the attenuated light beam. Specifically, the laser diffusion unit can be a lens group composed of aspheric lenses. The laser diffusion unit is used to diffuse the diameter of the coupled light beam to ≥2 cm to ensure the measurement of the surface of the liquid film to be measured.

[0020] Furthermore, the non-transmissive plate and the laser diffusion unit may be arranged vertically. The non-transmissive plate may be a metal sheet, a non-transmissive plastic sheet, or the like.

[0021] Furthermore, the laser beam splitter unit is arranged at the intersection of the laser diffusion unit and the non-transmissive plate in the vertical direction. The laser beam splitter unit can reflect the incident light beam emitted from the laser diffusion unit so that it is vertically irradiated onto the non-transmissive plate. In actual use, the laser beam splitter unit can be a 50R / 50T beam splitter. Depending on the use environment, a beam splitter with different reflectivity and transmittance can be selected.

[0022] Furthermore, the imaging unit is arranged on the transmission light path of the laser spectrometer unit, and is used to receive the image reflected by the non-transmission plate and transmit the image to the computer for processing. In actual use, the imaging unit can be a near infrared camera, such as a SWIR short wave infrared camera.

[0023] Further, the liquid film parameters include at least one of the liquid film thickness, the liquid film temperature and the liquid film concentration. For example, the above device can be used to solve the two-dimensional distribution images of the liquid film thickness, the liquid film temperature and the liquid film concentration respectively. The above device can also be used to simultaneously solve the two-dimensional distribution images of the liquid film thickness and the liquid film temperature, or the liquid film temperature and the liquid film concentration, or the liquid film thickness and the liquid film concentration. The above device can also be further used to simultaneously solve the two-dimensional distribution images of the liquid film thickness, the liquid film temperature and the liquid film concentration. It is worth noting that the device proposed by the present invention is not limited to the measurement of the above-listed parameters.

[0024] In a second aspect, the present invention discloses a measurement method using the above-mentioned non-transmission surface liquid film parameter imaging device based on absorption spectroscopy, wherein the measurement method can obtain a two-dimensional distribution image of at least one liquid film parameter, and the measurement method comprises the following steps:

[0025] According to the absorption spectrum property of the liquid film to be measured and the number of liquid film parameters to be solved, the selected wavelength is determined, and the number of selected wavelengths is ≥ the number of liquid film parameters to be solved;

[0026] According to the solved liquid film parameters, set the fitting equation of liquid film parameters and absorption coefficient at the selected wavelength, and get k λi =f λi (X), where i is the serial number of the selected wavelength, X is a certain liquid film parameter, including liquid film temperature, liquid film concentration, etc., k λi The liquid film to be measured is X when the liquid film parameter is X. i The incident light absorption coefficient; for example, when X is the liquid film temperature, the fitting equation is k λi =f λi (T), when X is the liquid film concentration, the fitting equation is k λi =f λi (C); When it is necessary to measure multiple liquid film parameters at the same time, each liquid film parameter and the absorption coefficient can be fitted separately to obtain the corresponding fitting equation;

[0027] When the device does not carry the liquid film to be tested, the device obtains the background images P corresponding to different selected wavelengths. 0i ;

[0028] When the device carries the liquid film to be tested, the device obtains the test images P corresponding to different selected wavelengths. ti ;

[0029] Analyze background image P 0i And the test image P ti The grayscale information in the image is used to construct the relationship between the grayscale value and the liquid film parameters, and combined with k λi =f λi (T), calculate the value and two-dimensional distribution image of the liquid film parameters of each pixel in the test image.

[0030] Further, analyze the background image P 0i And the test image P ti The grayscale information in the image is used to construct the relationship between the grayscale value and the liquid film parameters, and combined with k λi =f λi (X), calculate the values ​​and two-dimensional distribution images of each pixel and liquid film parameter in the test image, including:

[0031] Get background image P 0i The gray value H of each pixel0i(m,n) , get the test image P ti The gray value H of each pixel ti(m,n) ;

[0032] The inversion equation is constructed based on the Beer-Lambert law combined with the Fresnel formula: Among them, R i(m,n) is the reflectivity of light at the interface between water and air, μ i(m,n) is the light intensity attenuation caused by other factors, k λi is the absorption coefficient, T (m,n) is the liquid film temperature, C (m,n) is the liquid film concentration, d (m,n) is the thickness of the liquid film;

[0033] According to the selected wavelength k λi =f λi (X) and Calculate the value and two-dimensional distribution image of the liquid film parameters of each pixel in the test image.

[0034] Furthermore, when the liquid film concentration of the liquid film to be measured is known and the liquid film parameters to be solved are the liquid film temperature and the liquid film thickness, the measurement method includes the following steps:

[0035] Determine three selected wavelengths λ1, λ2, and λ3 according to the absorption spectrum properties of the liquid film to be tested;

[0036] According to the three selected wavelengths λ1, λ2, and λ3, the absorption coefficient of the liquid film to be tested at different temperatures is fitted, and k is obtained. λi =f λi (T), i = 1, 2, 3;

[0037] When the device does not carry the liquid film to be tested, the device obtains the corresponding background images P at the selected wavelengths λ1, λ2, and λ3 respectively. 0i , i=1,2,3;

[0038] When the device carries the liquid film to be tested, the device obtains the corresponding test images P at the selected wavelengths λ1, λ2, and λ3 respectively. ti , i=1,2,3;

[0039] Get background image P 0i The gray value H of each pixel in 0i(m,n) , get the test image P ti The gray value H of each pixel in ti(m,n) ;

[0040] Based on the Beer-Lambert law and the Fresnel formula, the inversion equation is constructed and solved at the selected wavelength to obtain:

[0041]

[0042]

[0043]

[0044] Combined with k λi =f λi (T) Solve the numerical value and two-dimensional distribution image of liquid film temperature and liquid film thickness.

[0045] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0046] 1. This application sets a laser spectrometer unit so that the incident light and the reflected light are arranged coaxially and perpendicularly to the non-transmissive flat plate. There is no need to consider the refraction caused when the laser is incident on the gas-liquid interface at a certain angle, which improves the calculation accuracy and simplifies the algorithm. The incident light and the reflected light are arranged coaxially and perpendicularly to the non-transmissive flat plate, which can make the imaging device layout structure more compact and the system more robust. The laser spectrometer unit is matched with the imaging unit so that the imaging unit can collect all the light intensity change information of the liquid film to be tested on the non-transmissive flat plate and present it in a grayscale photo for computer analysis and calculation to obtain a two-dimensional distribution image of the liquid film parameters.

[0047] 2. The measurement method of the present invention, at a preferred selected wavelength, uses a computer to analyze the grayscale information of each pixel of the corresponding image on the surface of the non-transmitting flat plate with and without the liquid film to be tested, constructs the relationship between the grayscale value and each parameter to be tested, calculates the specific value of the liquid film parameter to be tested at each pixel, obtains a two-dimensional distribution image of each liquid film parameter, and thus realizes high-precision synchronous imaging of multiple liquid film parameters on the surface of the non-transmitting flat plate.

[0048] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] 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.

[0050] Figure 1 is a schematic diagram of an imaging device in Embodiment 1 of the present invention;

[0051] Figure 2 It is a flow chart of the measurement method in the second embodiment of the present invention.

[0052] The figure marks of the above drawings are: 1. laser emitting unit; 2. laser coupling unit; 3. first attenuation unit; 4. optical fiber; 5. collimating lens; 6. second attenuation unit; 7. laser diffusion unit; 8. laser spectrometer unit; 9. non-transmissive plate; 10. imaging unit; 11. computer. DETAILED DESCRIPTION

[0053] 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.

[0054] Example 1: See Figure 1 As shown, a non-transmissive surface liquid film parameter imaging device based on absorption spectrum can solve at least one liquid film parameter, and the liquid film parameter includes liquid film thickness, liquid film temperature, liquid film concentration, etc. The imaging device includes a laser emitting unit 1, a laser coupling unit 2, a laser attenuation unit, a laser diffusion unit 7, a non-transmissive flat plate 9, a laser spectroscopic unit 8, an imaging unit 10 and a computer 11.

[0055] The laser emitting unit 1 includes a laser controller and a plurality of semiconductor lasers connected to the laser controller. The number of the semiconductor lasers can be determined according to the number of liquid film parameters that need to be solved. For example, when solving the two-dimensional distribution image of the liquid film temperature, two semiconductor lasers capable of emitting different wavelengths can be set in the device. When it is necessary to solve the two-dimensional distribution images of the liquid film temperature and the liquid film thickness simultaneously, three semiconductor lasers capable of emitting different wavelengths can be set in the device. The plurality of semiconductor lasers can emit laser beams of different wavelengths to achieve the solution of the liquid film parameters under the preferred wavelength combination.

[0056] The laser coupling unit 2 is connected to the laser emitting unit 1 , and the laser coupling unit 2 includes a wavelength division multiplexer, which is connected to the semiconductor laser via an optical fiber 4 and is used to couple multiple laser beams of different wavelengths emitted by the laser emitting unit 1 into one optical fiber 4 .

[0057] The laser attenuation unit includes a first attenuation unit 3, a collimating lens 5, and a second attenuation unit 6, which are arranged in sequence. The first attenuation unit 3 is an optical fiber attenuator, one end of which is connected to the laser coupling unit 2 via an optical fiber 4, and the other end of which is connected to the collimating lens 5 via a single-mode optical fiber. The first attenuation unit 3 is used to attenuate the laser intensity of the light beam emitted from the laser coupling unit 2. The second attenuation unit 6 is a NIR neutral density filter. The second attenuation unit 6 is arranged on the light path emitted from the collimating lens 5. The second attenuation unit 6 is used to further attenuate the laser intensity of the light beam emitted from the collimating lens 5.

[0058] The laser diffusion unit 7 is arranged on the optical path of the light beam emitted by the second attenuation unit 6. The laser diffusion unit 7 is used to widen the diameter of the attenuated light beam. The laser diffusion unit 7 is a lens group composed of aspherical lenses. The diameter of the coupled light beam widened by the laser diffusion unit 7 is ≥2 cm.

[0059] The non-transmissive plate 9 is disposed below the laser diffusion unit 7 , and an axis of the non-transmissive plate 9 is perpendicular to an axis of the laser diffusion unit 7 .

[0060] The laser spectrometer unit 8 is a spectroscope. The angles between the surface of the laser spectrometer unit 8 and the axes of the non-transmitting plate 9 and the laser diffusion unit 7 are all 45°. The laser spectrometer unit 8 can reflect the incident light beam emitted from the laser diffusion unit 7 so that it is irradiated vertically onto the non-transmitting plate 9, and reflected back to the laser spectrometer unit 8 on the non-transmitting plate 9. The laser spectrometer unit 8 can make the incident light and the reflected light coaxially perpendicular to the non-transmitting plate 9, and there is no need to consider the refraction generated when the laser is incident on the gas-liquid interface at a certain angle, which improves the calculation accuracy and simplifies the algorithm. The incident light and the reflected light are arranged coaxially and vertically to the non-transmitting plate 9, which can make the imaging device layout structure more compact and the system more robust.

[0061] The imaging unit 10 is disposed on the side of the laser beam splitting unit 8 facing away from the non-transmissive plate 9 and is located on the transmission light path of the laser beam splitting unit 8. The imaging unit 10 is used to receive the transmission light beam, convert it into a grayscale image, and transmit it to the computer 11 for processing. The imaging unit 10 is a near-infrared camera.

[0062] Embodiment 2: A method for measuring parameters of a liquid film on a non-transmissive surface. Taking pure water as an example, the specific steps for calculating the liquid film temperature and the liquid film thickness include:

[0063] S1: Determine the selected wavelength;

[0064] According to the absorption coefficient of pure water at different wavelengths at different temperatures, the selected wavelengths λ1, λ2, and λ3 are determined. When the wavelength is λ1, the absorption coefficient is minimized, which is used to remove or reduce background attenuation (such as refraction, reflection in the background light path, and contamination of optical components, etc.); when the wavelength is λ2, the absorption coefficient does not change with temperature; when the wavelength is λ3, the absorption coefficient changes the most with temperature.

[0065] S2: Fitting the absorption coefficient of pure water liquid film at different temperatures at the selected wavelength;

[0066] The above steps specifically include:

[0067] Under the conditions of wavelengths of λ2 and λ3, the absorption coefficient of pure water liquid film at different temperatures is fitted with temperature, and the relationship between the absorption coefficient and temperature at different wavelengths is obtained, k λi =f λi (T), where i is the serial number of the selected wavelength, k λi Indicates the wavelength λ of the liquid film to be measured at temperature T i The absorption coefficient of incident light.

[0068] S3: obtaining a background image when no pure water liquid film is carried;

[0069] The above steps specifically include:

[0070] No pure water film is set on the non-transmitting plate of the imaging device, and the laser emitting unit is controlled by the time division method to emit laser beams of selected wavelengths λ1, λ2, and λ3. The laser beam passes through the laser coupling unit, the laser attenuation unit, the laser diffusion unit, the non-transmitting plate, and the laser spectrometer in sequence. When the imaging unit collects wavelengths λ1, λ2, and λ3 respectively, the background image P of the non-transmitting plate without a pure water film is shown in FIG. 01 , P 02 , P 03 , and upload it to the computer for storage.

[0071] S4: Acquire test images when carrying a pure water liquid film;

[0072] The pure water to be tested is sucked by a dropper and dropped on the non-transmitting plate to form a pure water liquid film. The laser emission unit is controlled by the time division method to emit laser beams of selected wavelengths λ1, λ2, and λ3. The laser beam passes through the laser coupling unit, the laser attenuation unit, the laser diffusion unit, the pure water liquid film, the non-transmitting plate, and the laser spectrometer unit in sequence. When the imaging unit collects the wavelengths λ1, λ2, and λ3 respectively, the test image P of the pure water liquid film set in the test area on the non-transmitting plate t1 , P t2 , P t3 , and upload it to the computer for storage.

[0073] S5: Obtain a two-dimensional distribution image of liquid film temperature and liquid film thickness.

[0074] The collected background image P is processed by computer 01 , P 02 , P 03 And the test image P t1 , P t2 , P t3 Processing is performed to record each pixel in the image as an independent unit. Background image P 0i The gray value of each pixel in (i=1,2,3) is recorded as H 0i(m,n) , that is, H 01(m,n) , H 02(m,n) , H 03(m,n) . Test image P ti The gray value of each pixel in (i=1,2,3) is recorded as H ti(m,n) , that is, H t1(m,n) , H t2(m,n) , H t3(m,n) .

[0075] Based on the Beer-Lambert law and the Fresnel formula, the inversion equation is constructed and solved at the selected wavelength to obtain:

[0076]

[0077]

[0078]

[0079] Combined with k λi =f λi (T), solve for the values ​​of the film temperature and film thickness of the pure water film.

[0080] Arrange the original image pixel matrix, import the parameter value matrix into Origin for plotting, or use MATLAB or Python to program and plot the two-dimensional distribution diagram of each parameter.

[0081] According to the absorption spectrum-based non-transmitting surface liquid film parameter imaging device and the synchronous imaging measurement method of the liquid film thickness and liquid film temperature of the non-transmitting surface pure water liquid film provided in the embodiment, since a laser spectrometer unit is arranged in the imaging device, the incident light and the reflected light can be arranged coaxially and perpendicularly to the non-transmitting flat plate, which simplifies the complex optical path analysis when the light beam passes through the liquid film (such as refraction at the gas-liquid interface and reflection at a certain angle), and reduces the difficulty of thickness calculation; since the imaging unit collects image information within a certain area, it meets our needs for obtaining various parameters of the two-dimensional plane, and realizes the collection and analysis of the light intensity signal of the liquid film on the two-dimensional plane, thereby obtaining the two-dimensional distribution of the temperature and thickness of the pure water liquid film to be measured on the surface of the non-transmitting flat plate.

[0082] Of course, the non-transmissive surface liquid film parameter imaging device based on absorption spectrum and the liquid film thickness and liquid film temperature synchronous imaging measurement method of the non-transmissive surface pure water liquid film provided by the present invention are not limited to the structure and steps described in this embodiment. In the actual measurement process, the liquid film parameters to be measured are not limited to the liquid film thickness and liquid film temperature. For example, the liquid film concentration can also be measured synchronously. According to actual needs, the number of laser light sources in the laser emission unit is increased, and the inversion model of multiple parameters to be measured is re-established. Then, the device in the present invention is combined with the algorithm to image the various parameters of the liquid film to be measured, and a two-dimensional distribution image of the parameters to be measured can be obtained.

[0083] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A non-transmission surface liquid film parameter imaging device based on absorption spectroscopy, characterized in that: include: A laser emitting unit, wherein the laser emitting unit can provide at least two laser beams of different wavelengths; A laser coupling unit, connected to the laser emitting unit, for coupling laser beams of different wavelengths emitted by the laser emitting unit into a coupled beam; A laser attenuation unit, connected to the laser coupling unit, and used to reduce the laser intensity of the coupled light beam; A laser diffusion unit, disposed on the beam transmission path of the laser attenuation unit, for diffusing the diameter of the coupled beam to an incident beam of a preset size; A non-transmitting flat plate, used for carrying the liquid film to be measured and reflecting the incident light beam into a reflected light beam; A laser beam splitter unit is disposed at a position where both the incident light beam and the reflected light beam pass through, and is used to reflect the incident light beam onto the non-transmitting plate and enable the reflected light beam to penetrate to form a transmitted light beam; An imaging unit, used for receiving the transmitted light beam and converting it into a grayscale image; The computer is connected to the imaging unit and is used for receiving the grayscale image transmitted by the imaging unit and processing it to obtain a two-dimensional distribution image of the liquid film parameters.

2. The non-transmission surface liquid film parameter imaging device based on absorption spectrum according to claim 1, characterized in that: The laser attenuation unit comprises a first attenuation unit, a collimating lens and a second attenuation unit which are arranged in sequence.

3. The non-transmission surface liquid film parameter imaging device based on absorption spectrum according to claim 2, characterized in that: The first attenuation unit is a fiber optic attenuator.

4. The non-transmission surface liquid film parameter imaging device based on absorption spectrum according to claim 2, characterized in that: The second attenuation unit is a NIR neutral density filter.

5. The non-transmission surface liquid film parameter imaging device based on absorption spectrum according to claim 1, characterized in that: The laser diffusion unit is used to diffuse the diameter of the coupled light beam to ≥2 cm.

6. The non-transmission surface liquid film parameter imaging device based on absorption spectrum according to claim 1, characterized in that: The imaging unit is a near infrared camera.

7. The non-transmission surface liquid film parameter imaging device based on absorption spectrum according to claim 1, characterized in that: The liquid film parameters include at least one of liquid film thickness, liquid film temperature and liquid film concentration.

8. A measurement method using the non-transmission surface liquid film parameter imaging device based on absorption spectrum according to any one of claims 1 to 7, characterized in that: The measuring method can obtain a two-dimensional distribution image of at least one liquid film parameter, and the measuring method comprises the following steps: According to the absorption spectrum property of the liquid film to be measured and the number of liquid film parameters to be solved, the selected wavelength is determined, and the number of selected wavelengths is ≥ the number of liquid film parameters to be solved; According to the solved liquid film parameters, set the fitting equation of liquid film parameters and absorption coefficient at the selected wavelength, and get k λi =f λi (X), where i is the serial number of the selected wavelength, X is a certain liquid film parameter, X includes liquid film temperature, liquid film concentration, k λi The liquid film to be measured is X when the liquid film parameter is X. i The incident light absorption coefficient; When the device does not carry the liquid film to be tested, the device obtains the background images P corresponding to different selected wavelengths. 0i ; When the device carries the liquid film to be tested, the device obtains the test images P corresponding to different selected wavelengths. ti ; Analyze background image P 0i And the test image P ti The grayscale information in the image is used to construct the relationship between the grayscale value and the liquid film parameters, and combined with k λi =f λi (X), calculate the value and two-dimensional distribution image of the liquid film parameters of each pixel in the test image.

9. The measuring method according to claim 8, characterized in that: Analyze background image P 0i And the test image P ti The grayscale information in the image is used to construct the relationship between the grayscale value and the liquid film parameters, and combined with k λi =f λi (X), calculate the values ​​and two-dimensional distribution images of each pixel and liquid film parameter in the test image, including: Get background image P 0i The gray value H of each pixel 0i(m,n) , get the test image P ti The gray value H of each pixel ti(m,n) ; The inversion equation is constructed based on the Beer-Lambert law combined with the Fresnel formula: Among them, R i(m,n) is the reflectivity of light at the interface between water and air, μ i(m,n) is the light intensity attenuation caused by other factors, k λi is the absorption coefficient, T (m,n) is the liquid film temperature, C (m,n) is the liquid film concentration, d (m,n) is the liquid film thickness; According to the selected wavelength k λi =f λi (X) and Calculate the value and two-dimensional distribution image of the liquid film parameters of each pixel in the test image.

10. The measuring method according to claim 8, characterized in that: When the liquid film concentration of the liquid film to be measured is known and the liquid film parameters to be solved are the liquid film temperature and the liquid film thickness, the measuring method comprises the following steps: Determine three selected wavelengths λ1, λ2, and λ3 according to the absorption spectrum properties of the liquid film to be tested; According to the three selected wavelengths λ1, λ2, and λ3, the absorption coefficient of the liquid film to be tested at different temperatures is fitted, and k is obtained. λi =f λi (T), i = 1, 2, 3; When the device does not carry the liquid film to be tested, the device obtains the corresponding background images P at the selected wavelengths λ1, λ2, and λ3 respectively. 0i , i=1,2,3; When the device carries the liquid film to be tested, the device obtains the corresponding test images P at the selected wavelengths λ1, λ2, and λ3 respectively. ti , i=1,2,3; Get background image P 0i The gray value H of each pixel in 0i(m,n) , get the test image P ti The gray value H of each pixel in ti(m,n) ; Based on the Beer-Lambert law and the Fresnel formula, the inversion equation is constructed and solved at the selected wavelength to obtain: Combined with k λi =f λi (T) Solve the numerical value and two-dimensional distribution image of liquid film temperature and liquid film thickness.

Images