Flame multispectral imaging measurement apparatus, system and method based on fiber optic image bundle

Abstract

The application discloses a flame multispectral imaging measurement device, system and method based on an optical fiber image transmission beam, relates to the technical field of radiation imaging measurement, and solves the technical problem that different wavelength images cannot be acquired at the same time.The technical scheme is characterized in that different wavelength filter plates are arranged in front of an objective lens of the optical fiber image transmission beam.Compared with the existing radiation imaging technology, the amount of information acquired in the spectral dimension is increased, so that the accuracy of the to-be-measured field reconstruction is improved.In addition, in order to solve the problem that the traditional multispectral measurement scheme cannot guarantee that the acquired images are consistent in time, the optical fiber image transmission beam system is used for simultaneous acquisition of multispectral images, so that the time resolution and the spatial resolution of the measurement are increased, and the application value of the measurement of the temperature and the soot concentration of the flame at the tail nozzle of an aerospace engine or other jet flames is important.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radiation imaging measurement, in particular to a flame multi-spectral imaging measurement device, system and method based on an optical fiber image transmission beam. BACKGROUND

[0002] An aero-engine is a complex and precise thermodynamic machine, and the combustion condition of the aero-engine directly affects the performance, reliability and economy of the aircraft. The combustion chamber is an important component indispensable to the engine. When designing the combustion chamber, it is necessary to ensure good combustion stability, high combustion efficiency and low emission pollution. In order to improve the rationality of the combustion chamber design and the efficiency of the engine, it is necessary to measure the flame at the engine tail nozzle where the direct reaction combustion chamber condition is located. The temperature distribution is the most direct parameter of the reaction flame state. The aviation kerosene used by the aero-engine will form soot particles due to incomplete combustion, and therefore the soot concentration can also be one of the design bases. Therefore, the measurement of the temperature and soot concentration of the flame is crucial for the combustion diagnosis of the aero-engine.

[0003] There are many existing methods for temperature measurement and soot measurement, mainly divided into invasive and non-invasive methods. The methods capable of simultaneously measuring temperature and soot concentration include laser-based methods, thermocouple particle density methods and radiation spectrum-based methods. The thermocouple particle density method is an invasive measurement technology, which greatly affects the flow field characteristics of the measurement area itself. At the same time, due to its slow response speed and large error, it is not suitable for the measurement of the aero-engine. All laser-based methods require an external laser light source and an initial signal, and also require the arrangement of a corresponding receiver. Therefore, in industrial measurement applications, the light path arrangement is complex and the light path calibration is difficult. The radiation imaging technology is a non-invasive measurement technology based on flame image processing, which has the advantages of large amount of projection data acquisition, no need for external light source and good noise resistance, and is a measurement technology more suitable for the measurement of the aero-engine tail nozzle.

[0004] In order to measure the temperature and soot concentration with higher precision, multiple spectral information needs to be collected for fitting to avoid errors caused by model calculation. The traditional multi-spectral method is mainly used in steady-state flames, and the method for obtaining multi-spectrum is to replace the filter. However, in engine measurement, the flame at the tail nozzle is a jet flame, and this method cannot guarantee that the flame state reflected by the pictures obtained at different wavelengths is the same. Therefore, there is an urgent need for a device and method for measuring flame multi-spectral imaging to obtain more accurate three-dimensional temperature and soot concentration distribution of the flame. SUMMARY

[0005] The application provides a flame multispectral imaging measurement device, system and method based on an optical fiber image transmission beam, and the technical objective is achieved by the optical fiber image transmission beam system, the flame images at the same wavelength at different angles are obtained, and the spatial resolution of the flame is increased; meanwhile, the images at different wavelengths at different angles are obtained, and the three-dimensional temperature and soot concentration distribution of the reconstructed flame are more accurately obtained.

[0006] The above technical objective of the application is achieved by the following technical scheme:

[0007] A flame multispectral imaging measurement device based on an optical fiber image transmission beam comprises one-ninth optical fiber image transmission beams, each optical fiber image transmission beam is provided with a corresponding objective lens, and a filter plate is arranged in front of each objective lens; a view mirror is arranged at the convergence position of all the optical fiber image transmission beams, and a camera is connected to the view mirror; the camera is provided with a filter plate;

[0008] All the objective lenses are arranged in the same plane of 180 degrees in the to-be-measured area, the included angle between adjacent objective lenses is 20 degrees, and the image centers captured by each objective lens are at the same position; the objective lenses are divided into three groups in clockwise or counterclockwise order, each group comprises three objective lenses that are sequentially adjacent, each group of objective lenses is sequentially numbered in the same way, and the wavelengths of the filter plates in front of the objective lenses with the same number are the same.

[0009] A flame multispectral imaging measurement system based on an optical fiber image transmission beam comprises an optical fiber image transmission beam measurement system, the optical fiber image transmission beam measurement system comprises one-ninth optical fiber image transmission beams, each optical fiber image transmission beam is provided with a corresponding objective lens, and a filter plate is arranged in front of each objective lens; a view mirror is arranged at the convergence position of all the optical fiber image transmission beams, and a camera is connected to the view mirror, the camera is connected to a computing system; the camera is provided with a filter plate;

[0010] All the objective lenses are arranged in the same plane of 180 degrees in the to-be-measured area, the included angle between adjacent objective lenses is 20 degrees, and the image centers captured by each objective lens are at the same position; the objective lenses are divided into three groups in clockwise or counterclockwise order, each group comprises three objective lenses that are sequentially adjacent, each group of objective lenses is sequentially numbered in the same way, and the wavelengths of the filter plates in front of the objective lenses with the same number are the same.

[0011] A flame multispectral imaging measurement method based on an optical fiber image transmission beam comprises:

[0012] S1: arranging an optical fiber image transmission beam measurement system on a horizontal frame, the optical fiber image transmission beam measurement system comprises one-ninth optical fiber image transmission beams, the objective lens fields of the optical fiber image transmission beams are aligned, so that the image centers captured by each objective lens are at the same position, and the correspondence between the pixel coordinates (x p ,y p ) in the optical fiber image transmission beam and the real world physical coordinates (x r ,y r ) is established;

[0013] S2: the objective is divided into three groups in clockwise or counterclockwise order, each group includes three objectives in turn adjacent, each group of objectives is numbered in order, then the same wavelength filter is added in front of the objective with the same number;

[0014] S3: the image is captured by the camera and divided into the number of images matched with the number of objectives, nine different divided images in nine directions under three wavelengths are obtained;

[0015] S4: different wavelength filters are arranged in front of the camera respectively, the target surface of the black body furnace at different temperatures is captured by the camera with the filter, the gray value and the corresponding black body monochromatic radiation intensity under different wavelengths are obtained, the fitting relationship between the gray value and the black body monochromatic radiation intensity is obtained by fitting;

[0016] S5: the divided image is analyzed, and the optical fiber image transmission beam measurement system is assumed to be symmetrically arranged according to the symmetric flame, then six angle different flame information can be obtained for each wavelength, and the three-dimensional distribution of the flame temperature and the soot concentration to be measured is solved according to the image information of the flame.

[0017] The beneficial effects of the present application are that: compared with the existing radiation imaging technology, the present application increases the amount of information obtained in the spectral dimension, thereby improving the accuracy of the reconstruction of the measured field; in addition, in order to solve the problem that the traditional multi-spectral measurement scheme cannot guarantee that the obtained images are consistent in time, the optical fiber image transmission beam system is used for simultaneous acquisition of multi-spectral images, thereby increasing the time resolution and spatial resolution of the measurement, and the measurement of the temperature and soot concentration of the flame or other jet flames at the tail nozzle of the aerospace engine has important application value. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structural diagram of the measurement system described in the present application;

[0019] Figure 2 It is an imaging distribution diagram of the optical fiber image transmission beam described in the present application;

[0020] Figure 3 It is a flowchart of the measurement method described in the present application;

[0021] Figure 4 It is a flowchart of camera calibration in the present application;

[0022] Figure 5 It is a flowchart of radiation intensity calibration in the present application;

[0023] Figure 6 It is a schematic diagram of the reconstruction results of the flame temperature and the soot concentration;

[0024] Figure 7This is a schematic diagram comparing the measurement errors of this application with existing conventional methods. Detailed Implementation

[0025] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, the flame multispectral imaging measurement system based on fiber optic image bundles includes a fiber optic image bundle measurement system, which includes a 1-to-9 fiber optic image bundle. Each fiber optic image bundle is equipped with a corresponding objective lens, and each objective lens is equipped with a filter in front of it. A sight glass is provided at the junction of all fiber optic image bundles, and the sight glass is connected to a camera. The camera is connected to a computing system. The camera is equipped with a filter.

[0027] All objectives are placed in the same plane within a 180° range of the area to be measured, with an angle of 20° between adjacent objectives, and the center of the image captured by each objective is in the same position. The objectives are divided into three groups in clockwise or counterclockwise order, each group consisting of three adjacent objectives. The objectives in each group are numbered in the same order, so the wavelengths of the filters in front of the objectives with the same number are the same.

[0028] When performing measurements using the aforementioned fiber optic image bundle measurement system, the main steps include: (1) Arranging a 1:9 fiber optic image bundle at a certain plane in the area to be measured, ensuring that the objective lenses of the image bundle are at the same plane, for acquiring images of the area to be measured; (2) Numbering the objective lenses of the image bundle in a certain order, and setting up filters of the same wavelength in front of objective lenses with the same number; (3) Setting up a camera with a wavelength that meets the requirements behind the sight glass of the image bundle to capture images; (4) Collecting the captured images and transmitting them to the computing system for subsequent calculation and analysis.

[0029] The imaging distribution of the fiber optic image bundle in the camera is as follows Figure 2 As shown, imaging blocks 1, 4, and 7 correspond to flame images at imaging wavelength 1; imaging blocks 2, 5, and 8 correspond to flame images at imaging wavelength 2; and imaging blocks 3, 6, and 9 correspond to flame images at imaging wavelength 3.

[0030] like Figure 3 As shown, the flame multispectral imaging measurement method based on fiber optic image bundle includes:

[0031] S1: Arrange the fiber optic image bundle measurement system on a horizontal frame. This system includes a 1 / 9 fiber optic image bundle. Align the field of view of the objective lenses corresponding to the fiber optic image bundle so that the image center captured by each objective lens is at the same position, and establish the pixel coordinates (x, y, z) in the fiber optic image bundle. p ,y p ) and real-world physical coordinates (x r ,y r The correspondence between )

[0032] Specifically, the objective field of the optical fiber image bundle is aligned to make the center of the image captured by each objective lens in the same position, including:

[0033] S111: A plumb line is hung in the center of the region to be measured, and a mark is provided on the plumb line;

[0034] S112: The mark on the plumb line is captured by the nine objective lenses, and the images captured by the viewfinder are observed by the camera, and the objective lenses are adjusted to ensure that the center of each image captured by the viewfinder coincides with the mark on the plumb line;

[0035] S113: The adjusted objective lenses are fixed on the horizontal frame.

[0036] The camera calibration process is shown in Figure 4 , that is, the correspondence between the pixel coordinates (x p ,y p ) and the real world physical coordinates (x r ,y r ) in the optical fiber image bundle is established, including:

[0037] S121: A checkerboard is placed opposite the center objective lens in the center of the region to be measured, and the camera is focused to clearly capture the target surface pattern in the nine objective lenses;

[0038] S122: The camera captures the image at the viewfinder end, and according to the imaging principle of the optical fiber image bundle, the image is divided into nine images with the same number of objective lenses;

[0039] S123: Taking any corner point in the checkerboard as the coordinate origin, the two-dimensional physical coordinates (x r ,y r ) of all corner points on the checkerboard plane are obtained;

[0040] S124: The pixel coordinates (x pi ,y pi ) of the checkerboard in the nine images obtained by segmentation are obtained respectively, i=1,2,...,9, and the pixel coordinates (x pi ,y pi ) are fitted with the physical coordinates (x r ,y r ) to obtain the linear parameters of the pixel coordinates (x pi ,y pi ) and the two-dimensional physical coordinates, which are represented as:

[0041]

[0042] Where (X,Y,Z) represents the physical coordinates of a corner point; (T x ,T yT z ) represents a translation vector, i.e. the pixel coordinates of the origin of the physical coordinate system in the camera; (C x ,C y ) represents the principal point of the image (assuming that the image center and the flame center are coincident, the principal point of the image, i.e. the point on the actual image coincident with the flame center, is a corrected value), i.e. the pixel coordinates of the intersection of the optical axis and the imaging plane; represents a rotation matrix, i.e. the angles of rotation around the three coordinate axes when the physical coordinates are transformed to be consistent with the pixel coordinate attitude;

[0043] S125: Substitute the physical coordinates (x r ,y r ) into equation (1) to obtain the pixel coordinates (x r1 ,y r1 ), calculate the difference between (x r1 ,y r1 ) and (x r ,y r ) and solve the difference coefficient;

[0044] S126: Correct the aberration by the difference coefficient;

[0045] S127: Repeat steps S121 to S126 until the result is stable, and the final output relationship is the corresponding relationship between the pixel coordinates (x pi ,y pi ) and the physical coordinates (x r ,y r ).

[0046] S2: Divide the objective lenses into three groups in clockwise or counterclockwise order, each group including three objective lenses in turn adjacent to each other, and each group of objective lenses is numbered in order, then add a filter of the same wavelength in front of the objective lenses with the same number;

[0047] S3: Capture images by the camera and divide the images into a number of images matching the number of objective lenses, to obtain nine different divided images in nine directions under three wavelengths;

[0048] S4: Set different wavelength filters in front of the camera, capture the target surface of the black body furnace at different temperatures by the camera with the filter, obtain the gray value and the corresponding black body monochromatic radiation intensity under different wavelengths, and fit the gray value and the black body monochromatic radiation intensity to obtain the fitting relationship between them.

[0049] The process of radiation intensity calibration is shown in Figure 5 , and specifically includes:

[0050] S41: Set a filter of a selected wavelength in front of the camera;

[0051] S42: presetting the blackbody furnace setting temperature, and then calculating the blackbody monochromatic radiation intensity under the blackbody furnace setting temperature and the selected wavelength according to the Planck blackbody radiation law, and the calculation formula is as follows:

[0052]

[0053] wherein I b,λ represents the blackbody monochromatic radiation intensity, and the unit is W / m 2 ; c1 represents the first radiation constant, and is taken as 3.742*10 8 W·μm 4 / m 2 ; c2 represents the second radiation constant, and is taken as 1.439*10 4 μm·K; λ represents the wavelength of the filter in front of the camera; T n represents the blackbody furnace setting temperature;

[0054] S43: capturing the target surface of the blackbody furnace under the blackbody furnace setting temperature by the camera with the filter, and obtaining the target surface image under the blackbody furnace setting temperature;

[0055] S44: extracting the gray value of the image under the blackbody furnace setting temperature and the selected wavelength;

[0056] S45: replacing the filter in front of the camera, and repeating steps S43 to S44;

[0057] S46: changing the blackbody furnace setting temperature, and repeating steps S42 to S44 until the upper limit of the gray value of the image captured by the camera is reached;

[0058] S47: fitting the obtained gray value under different wavelengths and the blackbody monochromatic radiation intensity to obtain the fitting relationship between the two.

[0059] S5: analyzing the divided images, and assuming that the optical fiber image transmission beam measurement system is symmetrically arranged according to the symmetric flame, so that six angle-different flame information can be obtained for each wavelength, and the three-dimensional distribution of the flame temperature and the soot concentration to be measured is solved according to the image information of the flame.

[0060] Specifically, step S5 includes:

[0061] S51: extracting the gray value of each divided image, and grouping the divided images with the same wavelength;

[0062] S52: selecting 4 pixels of the upper and lower pixels of the reference row in each divided image, calculating the average gray value of the 4 pixels, and then obtaining the monochromatic radiation intensity value according to the fitting relationship;

[0063] S53: calculating the radiation intensity value in the grid, including:

[0064] Discretize the area to be measured into a grid, and discretize each objective field of view of the fiber image bundle according to the field of view angle, and each discrete view is regarded as a ray, and the length of each ray in each grid is obtained, and then the total monochromatic radiation intensity I λ (m r ) of The calculation formula is represented as:

[0065]

[0066] wherein k λ (n) represents the smoke absorption coefficient of the grid; I b,λ (n) represents the monochromatic blackbody radiation intensity; H λ (n) represents the radiation source term, and the value is equal to the calculated radiation intensity value in the grid; I λ (m r ) represents the total monochromatic radiation intensity of the ray m r to the camera target surface;

[0067] According to the 9 angles captured by the fiber image bundle, the radiation discrete ray paths at the 9 angles are obtained, and are represented as:

[0068]

[0069] The size of the radiation intensity value in each grid is obtained by the inverse problem solving method, and the calculation formula is as follows:

[0070] A·x=b; (5)

[0071] wherein A represents a path matrix composed of the lengths of the rays passing through the network; b is the monochromatic radiation intensity value obtained in step S52; and x is the quantity to be solved, i.e., the radiation intensity value in each grid;

[0072] S54: solving the flame temperature and the smoke black concentration through the radiation intensity value in the grid, comprising:

[0073] I b,λ (n) is calculated according to the Planck blackbody radiation law, k λ (n) is calculated according to the Rayleigh approximation for small particle size in the Mie scattering theory, and the calculation formula is as follows:

[0074]

[0075] wherein E(m)=-Im[(m 2 -1) / (m 2 +2)], and m represents the complex refractive index of the smoke black; f vrepresents the soot concentration; substituting formula (2) and formula (5) into formula (4), the following formula (6) is obtained:

[0076]

[0077] Formula (7) is a flame temperature and soot concentration calculation formula at a certain wavelength, three equations as shown in formula (6) are obtained according to three wavelengths obtained by the optical fiber image transmission beam, and then the slope k and the intercept b of the straight line are obtained by linear fitting, so as to solve the flame temperature and soot concentration distribution, which is represented as:

[0078]

[0079] S55: correcting the calculated flame temperature and soot concentration by using regularization and smoothing method to obtain the two-dimensional distribution of the two;

[0080] S56: reselecting different reference lines, repeating the operations of the above steps S53 to S55, so as to obtain the two-dimensional distribution of the flame temperature and soot concentration at different flame heights, and finally obtaining the three-dimensional distribution of the flame temperature and soot concentration.

[0081] As shown in Figure 6 , five layers are selected as the reconstruction research object, each layer is divided into a 45*45 grid, a total of 10125 grids, and the temperature and soot concentration values in each grid are studied respectively, and the five-layer reconstruction results of the non-axisymmetric transient flame and the third-layer reconstruction results are shown in Figure 6 . Figure 6 It is shown in the middle that the temperature distribution gradually develops from low in the middle to high on both sides to high in the middle and low on all sides, while the soot concentration distribution shows an opposite trend, that is, the trend of high in the middle and low on all sides gradually develops into the distribution of low in the middle and high on all sides, which is in good agreement with the actual situation.

[0082] As shown in Figure 7 , five layers are selected as the reconstruction research object, each layer is divided into a 45*45 grid, a total of 10125 grids, and the reconstruction error in each grid is studied respectively. When the method of the application is used, the average reconstruction error of the flame temperature and soot concentration is 0.0374*10% and 0.377%, while the average reconstruction error of the traditional measurement method is 0.257% and 3.12% respectively, which is much higher than the method used in the application, thus the superiority of the measurement of the application can be seen.

[0083] The above is a demonstrative embodiment of the application, and the protection scope of the application is defined by the claims and their equivalents.

Claims

1. A flame multispectral imaging measurement method based on fiber optic image bundle, characterized in that, include: S1: Arrange the fiber optic image bundle measurement system on a horizontal frame. This system includes a 1 / 9 fiber optic image bundle. Align the field of view of the objective lenses corresponding to the fiber optic image bundle so that the image center captured by each objective lens is at the same position, and establish the pixel coordinates (x, y, z) in the fiber optic image bundle. p ,y p ) and real-world physical coordinates (x r ,y r The correspondence between ) S2: Divide the objective lenses into three groups in clockwise or counterclockwise order. Each group includes three adjacent objective lenses. Each group of objective lenses is numbered in the same order. Then, add a filter of the same wavelength in front of the objective lenses with the same number. S3: Capture an image using a camera and divide the image into a number of images matching the number of objectives, resulting in nine different divided images in nine directions at three wavelengths; S4: Set up filters of different wavelengths in front of the camera, capture the target surface of the blackbody furnace at different temperatures through the camera with the filter, obtain the gray value and the corresponding blackbody monochromatic radiation intensity at different wavelengths, fit the gray value and the blackbody monochromatic radiation intensity to obtain the fitting relationship between the two. S5: Analyze the segmented image, and assume symmetrical arrangement of the fiber optic image bundle measurement system based on the symmetrical flame. Then, each wavelength can obtain flame information from six different angles. Based on the flame image information, the three-dimensional distribution of the flame temperature and soot concentration to be measured is obtained. Step S5 includes: S51: Extract the grayscale value of each segmented image and group segmented images with the same wavelength into one group; S52: Select 2 pixels above and below the reference row in each segmented image, for a total of 4 pixels, and calculate the average gray value by averaging the gray values ​​of these 4 pixels. Then, obtain the monochromatic radiation intensity value according to the fitting relationship. S53: Calculate the radiation intensity values ​​in the grid, including: The area to be measured is discretized into a grid, and the field of view of each objective lens in the fiber optic image bundle is discretized according to the field of view angle. Each discretized line of view is regarded as a ray, and the length of each ray in each grid is obtained. Then the total monochromatic radiation intensity I of each ray λ (m r The formula for calculating ) is expressed as: Where, k λ (n) represents the black smoke absorption coefficient of the grid; I b,λ (n) represents the intensity of monochromatic blackbody radiation; H λ (n) represents the radiation source term, whose value is equal to the calculated radiation intensity value in the grid; I λ (m r ) represents ray m r The total monochromatic radiation intensity reaching the camera target surface; Based on the nine angles captured by the fiber optic image bundle, the discrete ray paths at the nine angles are obtained, and represented as follows: The magnitude of the radiation intensity value in each grid is obtained by solving the inverse problem, and the calculation formula is as follows: A·x=b; (5) Where A represents the path matrix, which is a matrix composed of the lengths of the rays passing through the network; b is the monochromatic radiation intensity value obtained in step S52; and x is the quantity to be solved, i.e., the radiation intensity value in each grid. S54: Solve for flame temperature and soot concentration using radiation intensity values ​​in the grid, including: I b,λ (n) is calculated using Planck's law of blackbody radiation, k λ (n) is calculated using the Rayleigh assumption for small particle sizes in Mie scattering theory, as shown in the following formula: Where, E(m)=-Im[(m 2 -1) / (m 2 +2)], m represents the complex refractive index of the smoke black; f v Indicates the concentration of black smoke; Substituting equations (2) and (5) into equation (4), we get: Equation (7) is the formula for calculating the flame temperature and soot concentration at a certain wavelength. Based on the three wavelengths obtained from the optical fiber image bundle, three equations as shown in Equation (6) are obtained. Then, the slope k and intercept b of the straight line are obtained by straight line fitting, thereby solving for the distribution of flame temperature and soot concentration, which is expressed as: S55: The calculated flame temperature and soot concentration are corrected using regularization and smoothing methods to obtain their two-dimensional distributions; S56: Select different reference rows and repeat the above steps S53 to S55 to obtain the two-dimensional distribution of flame temperature and soot concentration at different flame heights, and finally obtain the three-dimensional distribution of flame temperature and soot concentration.

2. The measurement method as described in claim 1, characterized in that, In step S1, aligning the field of view of the objective lenses corresponding to the fiber optic image bundle so that the center of the image captured by each objective lens is at the same position includes: S111: A plumb line is suspended from the center of the area to be measured, and a mark is placed on the plumb line; S112: Use nine objective lenses to capture the marks on the vertical line, observe the images captured by the viewing mirror through the camera, adjust the objective lenses, and ensure that the center of each image captured by the viewing mirror coincides with the mark on the vertical line; S113: Fix the adjusted objective lens end on the horizontal frame.

3. The measurement method as described in claim 2, characterized in that, In step S1, the pixel coordinates (x, y, y) in the optical fiber image transmission bundle are established. p ,y p ) and real-world physical coordinates (x r ,y r The correspondences include: S121: Place a checkerboard pattern in the center of the area to be tested, directly opposite the central objective lens, and focus the camera to a position where the target pattern in the nine objective lenses can be clearly captured. S122: The camera captures the image at the viewing end and, according to the fiber optic image bundle imaging principle, divides the image into nine images, the same number as the objective lens. S123: Using any corner point in the chessboard as the origin, obtain the two-dimensional physical coordinates (x, y, y) of all corner points on the chessboard plane. r ,y r ); S124: Obtain the pixel coordinates (x, y, z) of the checkerboard pattern in the nine segmented images. pi ,y pi ), i = 1, 2, ..., 9, set the pixel coordinates (x pi ,y pi ) respectively with physical coordinates (x r ,y r By fitting the data, the pixel coordinates (x, y) are obtained. pi ,y pi The line type parameters of the two-dimensional physical coordinates are expressed as: Where (X,Y,Z) represents the physical coordinates of a corner point; (T) x ,T y ,T z () represents the translation vector, i.e., the pixel coordinates of the origin of the physical coordinate system in the camera; (C) x C y () represents the principal point of the image, that is, the pixel coordinates of the intersection of the optical axis and the imaging plane; This represents the rotation matrix, which is the angle of rotation around the three coordinate axes when the physical coordinates are transformed to match the pixel coordinate orientation. S125: Transfer physical coordinates (x r ,y r Substituting into equation (1), we obtain the pixel coordinates (x... r1 ,y r1 ), calculate (x r1 ,y r1 ) and (x r ,y r Find the difference and solve for the difference coefficient; S126: Correcting aberrations using difference coefficients; S127: Repeat steps S121 to S126 until the result stabilizes. The final output formula is the pixel coordinate (x... pi ,y pi ) and physical coordinates (x) r ,y r The correspondence between ).

4. The measurement method as described in claim 3, characterized in that, Step S4 includes: S41: Set a filter for a specific wavelength in front of the camera; S42: Set the blackbody furnace temperature, and then calculate the blackbody monochromatic radiation intensity at the set temperature and selected wavelength using Planck's blackbody radiation law. The calculation formula is as follows: Among them, I b,λ This represents the monochromatic radiation intensity of a blackbody, measured in W / m. 2 c1 represents the first radiation constant, which is taken as 3.742 × 10⁻⁶. 8 W·μm 4 / m 2 c2 represents the second radiation constant, which is taken as 1.439 × 10⁻⁶. 4 μm·K; λ represents the wavelength of the front filter of the camera; T n This indicates the set temperature of the blackbody furnace; S43: Capture the target surface of the blackbody furnace at the set temperature using a camera with a filter, and obtain an image of the target surface at the set temperature of the blackbody furnace. S44: Extract the grayscale values ​​of the image at the set temperature and selected wavelength of the blackbody furnace; S45: Replace the filter in front of the camera, and repeat steps S43 to S44; S46: Change the blackbody furnace setting temperature and repeat steps S42 to S44 until the upper limit of grayscale value of the image captured by the camera is reached. S47: Fit the obtained gray values ​​at different wavelengths with the blackbody monochromatic radiation intensity to obtain the fitting relationship between the two.

5. A flame multispectral imaging measurement device based on an optical fiber image bundle, characterized in that, The measuring device is used to implement the measuring method according to any one of claims 1-4. The measuring device includes a 1-to-9 fiber optic image transmission bundle, each fiber optic image transmission bundle is provided with a corresponding objective lens, and each objective lens is provided with a filter in front of it; a sight glass is provided at the junction of all fiber optic image transmission bundles, and a camera is connected to the sight glass; the camera is equipped with a filter. All objectives are placed in the same plane within a 180° radius of the area to be measured, with an angle of 20° between adjacent objectives, and the center of the image captured by each objective is in the same position. The objectives are divided into three groups in clockwise or counterclockwise order, each group consisting of three adjacent objectives. The objectives in each group are numbered in the same order, so the wavelengths of the filters in front of the objectives with the same number are the same.

6. A flame multispectral imaging measurement system based on an optical fiber image bundle, characterized in that, The measurement system is used to implement the measurement method according to any one of claims 1-4. The measurement system includes an optical fiber image bundle measurement system, which includes a 1-to-9 optical fiber image bundle. Each optical fiber image bundle is provided with a corresponding objective lens, and a filter is provided in front of each objective lens. A sight glass is provided at the junction of all optical fiber image bundles. The sight glass is connected to a camera, and the camera is connected to a computing system. The camera is equipped with a filter. All objectives are placed in the same plane within a 180° range of the area to be measured, with an angle of 20° between adjacent objectives, and the center of the image captured by each objective is in the same position. The objectives are divided into three groups in clockwise or counterclockwise order, each group consisting of three adjacent objectives. The objectives in each group are numbered in the same order, so the wavelengths of the filters in front of the objectives with the same number are the same.

Images