A method and device for calibrating a spectrographic laser-induced phosphorimaging system

Abstract

This invention discloses a calibration method and device for a spectroscopic laser-induced phosphorescence imaging system. The calibration method includes: selecting a homogenizing plate as a standard light source and placing the emitting surface of the homogenizing plate at the focal plane of the imaging system; setting the acquisition frequency, total acquisition time, and N different exposure times, and acquiring N sets of grayscale images obtained by the imaging system under different exposure times; averaging the pixel values ​​of the N sets of grayscale images to obtain the image grayscale matrix of each set of grayscale images; performing linear fitting using the least squares method on the set of grayscale matrices under the N exposure times to obtain the bias correction matrix and gain correction matrix; and correcting the original response grayscale matrix obtained under the test state based on the obtained bias correction matrix and gain correction matrix.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, specifically a method for wide-range response correction of a spectroscopic laser-induced phosphorescence imaging system. Background Technology

[0002] The high-temperature exhaust gas temperature at the turbine inlet of aero-engines has a significant impact on thrust-to-weight ratio, engine efficiency, and emissions per unit of fuel consumption. Accurate measurement of the high-temperature exhaust gas temperature field is necessary, but its complex flow field severely limits the application of traditional temperature measurement techniques. Laser-induced phosphorescence (LIP) temperature measurement technology is non-invasive, requires few optical windows, and has high reliability, making it a promising application for temperature field measurements involving complex flow and heat transfer processes where optical windows are limited.

[0003] Laser-induced phosphorescence (LIP) temperature measurement technology is a non-contact optical temperature measurement technique based on the phosphorescence thermal quenching effect. Currently, the more mature methods for LIP temperature measurement include the absolute intensity method, the lifetime decay method, and the intensity ratio method. The absolute intensity method measures temperature based on the characteristic that phosphorescence intensity decreases with increasing ambient temperature. It is suitable for temperature measurement scenarios where phosphorescent materials are uniformly distributed, such as spraying a uniformly thick phosphorescent coating onto a high-temperature solid wall. By measuring the phosphorescence intensity of the coating, the temperature distribution of the high-temperature solid wall can be indirectly measured. The lifetime decay method measures temperature based on the characteristic that phosphorescence lifetime decreases with increasing ambient temperature. It typically uses a high-speed camera to continuously acquire phosphorescence signals from the same measured area, fits the phosphorescence lifetime distribution, and inverts the temperature distribution of the solid wall based on the relationship between phosphorescence lifetime and ambient temperature. This method requires the test system to be relatively stationary with respect to the object being measured and is suitable for measuring stationary or rotating high-temperature solid walls. The intensity ratio method measures temperature using the relationship between the ratio of phosphorescence intensities in two different bands of the phosphorescence emission spectrum and the ambient temperature. It can be used for temperature measurement scenarios involving complex flow or uneven distribution of phosphorescent particles.

[0004] In summary, among laser-induced phosphorescence temperature measurement methods, the intensity ratio method is most suitable for measuring high-temperature gas temperature fields. Based on this technology, a spectroscopic laser-induced phosphorescence imaging system has been developed in recent years, such as... Figure 1 As shown, the system consists of a dichroic mirror, a cage plate (fixed dichroic mirror), a filter, a cage plate (fixed filter), a lens, and a CCD camera.

[0005] To verify the feasibility of measuring the gas temperature field using the laser-induced phosphorescence intensity ratio method, the laboratory designed and built a high-temperature jet experimental platform with a temperature of T≤500℃, and selected BAM:EU. 2+ Phosphorescent particles are used as a thermal imaging medium for temperature field measurement. BAM:EU 2+ The emission spectrum after excitation by a 355nm laser is as follows Figure 2As shown in the figure, the phosphorescence wavelength is mainly 400-500 nm. The phosphorescence intensity at 425±15 nm increases with increasing temperature, while the phosphorescence intensity at 466±18 nm remains essentially unchanged with increasing temperature. Using I... 425 I represents the phosphorescence intensity value at 425±15nm. 466 This represents the phosphorescence intensity value at 466±18nm. The laser-induced phosphorescence intensity ratio method for temperature measurement is based on the phosphorescence intensity ratio I... 425 / I 466 The temperature was measured in relation to the phosphorescent particles, as shown in equation (1). The 400-500nm phosphorescence emitted by the phosphorescent particles was divided into two bands, 400-445nm and 445nm-500nm, by a dichroic mirror. The 400-445nm phosphorescence was reflected by the 45° mirror surface of the dichroic mirror and then filtered by a 425±15nm filter before being imaged on CCD camera 1. The 445nm-500nm phosphorescence passed through the dichroic mirror and was filtered by a 466±18nm filter before being imaged on CCD camera 2. The temperature field can be retrieved by processing the gray values ​​of the two phosphorescent particle images of different bands obtained simultaneously by CCD camera 1 and CCD camera 2 using the intensity ratio method based on equation (1).

[0006] F = I 425 / I 466 =f(T) (1)

[0007] Ideally, under uniform illumination, the response of a spectrophotometric laser-induced phosphorescence imaging system should be completely consistent, meaning that the grayscale values ​​of the image pixels should be exactly equal. However, due to the influence of factors such as the optical system structure (the light-passing aperture of the cage plate fixing the dichroic mirror), the materials and manufacturing process of the CCD camera's photoelectric sensor, and the filtering parameters of the filter and dichroic mirror, the response of a spectrophotometric laser-induced phosphorescence imaging system exhibits significant spatial inhomogeneity. That is, the grayscale values ​​of the phosphorescence signal in the same area of ​​the measured object differ significantly when imaged on different pixels of the CCD camera, causing the intensity ratio method to fail to accurately deduce the temperature field distribution.

[0008] Currently, there is limited research on the causes and correction methods for spatial non-uniformity in the response of spectroscopic laser-induced phosphorescence imaging systems. In the field of CCD camera manufacturing, there is considerable research on methods for correcting non-uniformity in the photoelectric response of CCD cameras, such as one-point correction and two-point correction methods. However, these methods only correct the non-uniformity of the CCD camera within the imaging system. In spectroscopic laser-induced phosphorescence imaging systems, the system structure, the non-uniformity of the CCD camera's photoelectric response (inconsistent responses of the same pixel to different wavelengths of light, and inconsistent responses of different pixels to the same wavelength of light), lens parameters (replication ratio, aperture value), filter parameters, and dichroic mirror parameters all affect the system's response uniformity. Furthermore, there are coupling relationships between different components, making it difficult to meet the requirements for accurate temperature measurement through traditional single-component correction of the CCD camera. In addition, the phosphorescence signal intensity range within the measured flow field is large due to the influence of phosphorescent particle concentration and laser energy density. To ensure that the corrected imaging system is unaffected by the phosphorescence signal intensity, it is necessary to perform a wide-range correction of the imaging system response. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method and calibration device for wide-range correction of the response of a spectroscopic laser-induced phosphorescence imaging system to reduce temperature measurement error.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0011] This invention first provides a method for wide-range response correction of a spectroscopic laser-induced phosphorescence imaging system, comprising:

[0012] A light-diffusing plate that fills the entire field of view of the CCD camera is selected as the standard light source; the adjusted beam-splitting laser-induced phosphorescence imaging system is placed in front of the light-diffusing plate so that the light-emitting surface of the light-diffusing plate is located at the focal plane of the imaging system.

[0013] Set the acquisition frequency, total acquisition time, and N different exposure times, and acquire N sets of grayscale images obtained by the imaging system under different exposure times;

[0014] For the N sets of grayscale images collected, the average value of each pixel is used to obtain the image grayscale matrix (Y1Y2...Y1) of each set of grayscale images. N );

[0015] For the set of grayscale matrices (Y1 Y2...Y) under N exposure times N The bias correction matrix and gain correction matrix are obtained by linear fitting using the least squares method.

[0016] Based on the obtained bias correction matrix and gain correction matrix, the original response grayscale matrix obtained under the test state is corrected.

[0017] The specific steps of the method for wide-range response correction of a spectroscopic laser-induced phosphorescence imaging system according to the present invention are as follows:

[0018] A light-diffusing plate that fills the entire field of view of the CCD camera is selected as the standard light source; the adjusted beam-splitting laser-induced phosphorescence imaging system is placed in front of the light-diffusing plate so that the light-emitting surface of the light-diffusing plate is located at the focal plane of the imaging system.

[0019] Set the acquisition frequency, total acquisition time, and N different exposure times [x1, x2, ... x]. N N sets of grayscale images were acquired by the imaging system at different exposure times.

[0020] For the N sets of grayscale images collected, the average value of each pixel is used to obtain the image grayscale matrix (Y1Y2...Y1) of each set of grayscale images. N ); where Y o (where o is an integer and 1 ≤ o ≤ N) is:

[0021]

[0022] The steps involve using the least squares method to analyze the image grayscale matrix (Y1 Y2 ... Y...). N The pixel with the highest grayscale value y max Perform a linear fit; the linear fit formula is:

[0023]

[0024] In the formula, a max For the response gain coefficient, b max In response to the bias error, r max The linear fit is given by x, which is a constant light source intensity value, and the other variables are:

[0025]

[0026] In the formula, x N y represents the exposure time of the Nth grayscale image. maxN This represents the maximum gray value of a pixel in the Nth grayscale matrix;

[0027] Take y maxN This represents the maximum gray value of a pixel in the Nth gray-level matrix and serves as a calibration point.

[0028] The bias error and gain coefficient of the ideal response curve are determined as follows:

[0029] b max =(y max1 +y max2 +...+y maxN ) / Na max(x1+x2+...+x N ) / N

[0030] a max =((y max1 ·x1+y max2 ·x2+...+y maxN ·x N ) / N-(y max1 +y max2 +...+y maxN )·(x1+x2+...+x N ) / N 2 ) / ((x1 2 +x2 2 +...+x N 2 ) / N-(x1+x2+...+x N ) 2 / N 2 )

[0031] In the formula, b max The bias error of the ideal response curve; a max The gain coefficient of the ideal response curve;

[0032] Determine the grayscale matrix Y o Any pixel y i,j (i, j are integers and 1≤i≤m; 1≤j≤n) The bias error and gain coefficient of the response curve are respectively:

[0033] b i,j =(y i,j,1 +y i,j,2 +...+y i,j,N ) / Na i,j (x1+x2+...+x N )

[0034] a i,j =((y i,j,1 ·x1+y i,j,2 ·x2+...+y i,j,N ·x N ) / N-(y i,j,1 +y i,j,2 +...+y i,j,N )·(x1+x2+...+x N ) / N 2 ) / ((x1 2 +x2 2 +...+x N 2 ) / N-(x1+x2+...+x N ) 2 / N 2 )

[0035] In the formula, b i,j The bias error of the response curve, a i,j The gain coefficient of the response curve;

[0036] Determine the grayscale matrix Y o Any pixel y i,j (i, j are integers and 1≤i≤m; 1≤j≤n) The correction factor for the gain coefficient of the response curve is:

[0037] c i,j =a max / a i,j

[0038] For the set of grayscale matrices (Y1 Y2...Y) under N exposure times N Using the least squares method for linear fitting, the bias correction matrix B and the gain correction matrix C are obtained as follows:

[0039] B = (Y1 + Y2 + ... + Y) N ) / NA(x1+x2+...+x N ) / N

[0040] C = a max / A

[0041] In the formula, B is b i,j A is a set; i,j The set of is the gain matrix; C is c i,j A set;

[0042] The original response grayscale matrix Y is corrected based on the bias correction matrix B and the gain correction matrix C. The correction formula is as follows:

[0043] Y correction =(YB).*C

[0044] In the formula, Y correction This is the corrected grayscale matrix.

[0045] The present invention also provides a wide-range response correction device for a spectrophotometric laser-induced phosphorescence imaging system, comprising a processor and a memory; the memory stores a program or instructions, which are loaded and executed by the processor to implement the steps of the above-described wide-range response correction method for a spectrophotometric laser-induced phosphorescence imaging system.

[0046] Compared with the prior art, the present invention has the following advantages:

[0047] (1) Existing technologies only perform uniformity correction on the photoelectric sensor of CCD cameras, while this invention performs correction on the entire imaging system. To address the response space non-uniformity problem in the beam splitting laser-induced phosphorescence imaging system, a multi-point correction method for the imaging system is proposed based on the least squares linear fitting principle. The correction matrix of the imaging system is determined, and the response uniformity of the corrected imaging system is significantly improved. Based on the correction matrix of the imaging system, a phosphorescence intensity ratio temperature calibration experiment was carried out, and the relationship between phosphorescence intensity ratio and temperature was obtained. The calibration curve is monotonic, does not have multivalues, and conforms to the theoretical trend, providing the necessary premise for temperature field measurement. The temperature measurement results before and after the correction of the imaging system were verified by the jet two-dimensional temperature field measurement experiment. The temperature measurement error of the cold jet was reduced by 78% after correction compared with that before correction, indicating that the calibration method of the beam splitting laser-induced phosphorescence imaging system proposed in this paper has a good effect on improving the temperature measurement accuracy.

[0048] (2) This invention enables comprehensive calibration of a spectroscopic laser-induced phosphorescence imaging system. The dichroic mirror, cage plate (fixed dichroic mirror), filter, cage plate (fixed filter), lens, and CCD photoelectric sensor in the imaging system are equivalently represented as an imaging model of the lens and CCD photoelectric sensor. By selecting a light-diffusing plate large enough to fill the entire field of view of the imaging system as a standard light source, calibration of all positions within the field of view of the imaging system can be achieved. Adjusting the exposure time of the imaging system is equivalent to adjusting the intensity of the standard light source, and multi-point correction of the imaging system is achieved based on the least squares linear fitting principle, making the corrected imaging system applicable to a wider range of phosphorescence signal intensity. The least squares method increases the correction accuracy, and the obtained parameters are far fewer than those of traditional calibration methods, saving hardware resources, reducing system power consumption, and the algorithm structure is simple, computationally inexpensive, and easy to implement in hardware.

[0049] (3) Compared with existing technologies, the calibration process of this invention is convenient and fast. Traditional image sensor response uniformity correction uses an integrating sphere as the light source. The light source intensity is adjusted by adjusting the output power of the integrating sphere. After each adjustment, it is necessary to wait for the light source intensity to stabilize before signal acquisition can be performed. The system structure is complex and time-consuming. This invention can be equivalent to changing the standard light source intensity by adjusting the exposure time of the imaging system. Therefore, only a single-intensity datum plate is needed for imaging system calibration. The signal acquisition process does not require waiting, and the calibration process is convenient and fast.

[0050] (4) The calibration experimental device of this invention has a simple structure. This invention only requires placing a homogenizing plate on the existing temperature measurement system to calibrate the imaging system. After calibration, the homogenizing plate can be removed to conduct temperature measurement experiments, enabling real-time calibration in industrial settings. The calibration process is not easily affected by the temperature measurement environment. The calibrated system can be directly used for laser-induced phosphorescence temperature field measurement.

[0051] (5) High cost performance. The light-diffusing plates used in the method of this invention can all be common products on the market, with no special requirements, low cost, and accurate and fast calibration results, resulting in high cost performance.

[0052] (6) Wide range of applications. This invention is aimed at the response inhomogeneity correction of spectroscopic imaging systems. In addition to being applicable to the response inhomogeneity correction of spectroscopic laser-induced phosphorescence imaging systems, it is also applicable to the response inhomogeneity correction of multispectral imaging systems such as spectroscopic spectral radiometric thermometry imaging systems and spectroscopic laser-induced fluorescence imaging systems. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of a spectroscopic laser-induced phosphorescence imaging system;

[0054] Figure 2 This is the emission spectrum of BAM:EU2+ phosphorescent particles;

[0055] Figure 3 Diagram of calibration device for a beam-dispersive laser-induced phosphorescence imaging system;

[0056] Figure 4 Grayscale images of the imaging system response before and after correction, where (a) is before correction and (b) is after correction.

[0057] Figure 5 The results are for phosphorescence intensity ratio and temperature calibration.

[0058] Figure 6 The results show the two-dimensional temperature field measurement of the jet at 26℃; (a) is the grayscale image of phosphorescent particles in two bands of the cold jet temperature measurement experiment, (b) is the two-dimensional temperature distribution of the jet reconstructed based on the intensity ratio method, and (c) is the ratio of phosphorescent intensity in the radial direction of the cold jet before and after the imaging system is calibrated, as shown by the red line in (a). Detailed Implementation

[0059] The present invention will now be described in detail with reference to the accompanying drawings:

[0060] This embodiment provides a method for wide-range response correction of a spectroscopic laser-induced phosphorescence imaging system. The imaging system correction device used is described in [reference needed]. Figure 3 It includes two cameras, a dichroic mirror, a light homogenizer, and a displacement stage.

[0061] The homogenizing plate serves as the standard light source. Its size is large enough to fill the entire field of view of the CCD camera, and it is fixed by a displacement stage. Before calibration, the adjusted beam-splitting laser-induced phosphorescence imaging system is placed in front of the homogenizing plate, and the displacement stage that fixes the homogenizing plate is adjusted so that the light-emitting surface of the homogenizing plate is located at the focal plane of the imaging system.

[0062] The steps of the wide-range response correction method for a spectroscopic laser-induced phosphorescence imaging system are as follows:

[0063] Step 1: Set the imaging system signal acquisition frequency to 5Hz and the total acquisition time to 20s. Adjust the imaging system exposure time from 50μs to 1000μs at 50µs intervals, acquiring 100 grayscale images per group, for a total of 20 groups. The signal strength acquired by the camera is I = XT, where X is the light source intensity and T is the camera exposure time. Both adjusting the camera exposure time and adjusting the light source intensity can change the signal strength I; for simplicity, we will use adjusting the camera exposure time to change the signal strength I.

[0064] Step 2: Take the average pixel value of each group of 100 grayscale images to obtain the image grayscale matrix (Y1 Y2...Y ... 20 ); where Y o (where o is an integer and 1 ≤ o ≤ 20) is:

[0065]

[0066] In the formula, m and n represent the coordinates of the pixel;

[0067] Step 3: Use the least squares method to analyze the image grayscale matrix (Y1 Y2...Y...). 20 The pixel with the largest degree value y max Perform a linear fit; the linear fit formula is:

[0068]

[0069] In the formula, a max For the response gain coefficient, b max In response to the bias error, r max The linear fit is given by x, which is a constant light source intensity value, and the other variables are:

[0070]

[0071] In the formula, [x1,x2,...x 20 [] indicates the exposure time of the 20-group imaging system, i.e., [50μs, 100μs, ... 1000μs];

[0072] Step 4: Calculate the bias error and gain coefficient of the ideal response curve of the imaging system, respectively:

[0073] b max =(y max1 +y max2 +...+y max20 ) / 20-a max (x1+x2+...+x 20 ) / 20

[0074] a max =((y max1 ·x1+y max2 ·x2+...+y max20 ·x 20 ) / 20-(y max1 +y max2 +...+y max20 )·(x1+x2+...+x 20 ) / 400) / ((x1 2 +x2 2 +...+x 20 2 ) / 20-(x1+x2+...+x 20 ) 2 / 400)

[0075] In the formula, y max b is the maximum value in the image grayscale matrix Y, a predetermined marker; max The bias error of the ideal response curve; a max The gain coefficient of the ideal response curve;

[0076] Step 5: Calculate the value of any pixel y in the imaging system i,j The bias error, gain coefficient, and gain correction factor of the response curve are as follows:

[0077] b i,j =(y i,j,1 +y i,j,2 +...+y i,j,20 ) / 20-a i,j (x1+x2+...+x 20 )

[0078] a i,j =((y i,j,1 ·x1+y i,j,2 ·x2+...+y i,j,20 ·x 20 ) / 20-(y i,j,1 +y i,j,2 +...+y i,j,20 )·(x1+x2+...+x 20 ) / 400) / ((x1 2 +x2 2 +...+x 20 2 ) / 20-(x1+x2+...+x 20 ) 2 / 400)

[0079] c i,j =amax / a i,j

[0080] In the formula, b i,j For bias error; a i,j c is the gain coefficient. i,j This is the gain correction factor;

[0081] Step 6: Place any pixel y i,j The calculation process for the bias error, gain coefficient, and gain correction factor of the response curve is extended to all pixels for the grayscale matrix set (Y1 Y2...Y) at 20 exposure times. 20 The bias correction matrix and gain correction matrix are obtained by linear fitting using the least squares method, as follows:

[0082] B = (Y1 + Y2 + ... + Y) 20 ) / 20-A(x1+x2+...+x 20 ) / 20

[0083] C = a max / A

[0084] In the formula, B is b i,j The set of values, i.e., the bias correction matrix; C is the set of values ​​for c. i,j The set of values, i.e., the gain correction matrix; A is a i,j The set of, i.e., the gain matrix;

[0085] Step 7: Based on the bias correction matrix B and the gain correction matrix C, perform correction processing on the original response grayscale matrix Y. The correction formula is as follows:

[0086] Y correction =(YB).*C

[0087] In the formula, Y correction This is the corrected grayscale matrix. The results before and after correction are as follows: Figure 4 As shown.

[0088] Since laser-induced phosphorescence intensity ratio method temperature measurement is based on the characteristic that the phosphorescence intensity ratio decreases with increasing temperature, it is necessary to calibrate the phosphorescence intensity ratio at temperature before conducting temperature measurement experiments. The calibration procedure is as follows:

[0089] (1) Preparation of phosphorescent particle carrier slide. Weigh 50 mg of phosphorescent particles using a microbalance and pour them into a beaker containing 250 ml of purified water to prepare a phosphorescent particle solution. Use a dropper to draw a certain volume of phosphorescent particle solution and add it to a glass slide. Let it stand for 5 minutes until the phosphorescent particles in the solution are deposited on the surface of the glass slide. Use dry paper to remove the excess solution. The preparation of the phosphorescent particle glass slide is complete.

[0090] (2) Adjust the temperature of the temperature control chamber and heat the phosphorescent particle carrier plate. Place the prepared phosphorescent particle carrier plate into the temperature control chamber and fix it in place. Set the temperature of the temperature control chamber to 26℃, 50℃, 100℃, 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, and 525℃ in sequence.

[0091] (3) Acquiring phosphorescence signals. The temperature control box reaches the set temperature through PID regulation. After the temperature of the temperature control box stabilizes for 5 minutes, the laser triggering sequence and the two CCD cameras are controlled by the synchronous controller to acquire phosphorescence images.

[0092] (4) The original phosphorescence image was corrected using the imaging system correction matrices B and C obtained in Section 1.3, and the corrected phosphorescence image was processed using the intensity ratio method. The phosphorescence intensity ratio temperature calibration results are as follows: Figure 5 As shown.

[0093] To verify the effect of system calibration on improving temperature measurement accuracy, a two-dimensional temperature field measurement experiment of laser-induced phosphorescent jet was conducted. A 355nm laser was expanded into a 0.4mm thick fan-shaped beam using a sheet light source beam expander to excite phosphorescent particles in a free jet. Two CCD cameras simultaneously acquired phosphorescent images of the same measured area at two different wavelengths. After calibration using the system calibration matrix, a preprocessed image was obtained. The intensity ratio distribution of the two-dimensional phosphorescence in the jet was solved using the intensity ratio method. Based on... Figure 5 The two-dimensional temperature field distribution of the jet is solved by using the results of phosphorescence intensity ratio temperature calibration.

[0094] The error analysis of the cold-state experimental temperature measurement results is shown in Table 1.

[0095] Table 1 Error Analysis of Temperature Measurement Results

[0096]

[0097] The grayscale images of phosphorescent particles in two bands from the cold jet temperature measurement experiment are as follows: Figure 6 As shown in (a), the two-dimensional temperature distribution of the jet reconstructed based on the intensity ratio method is as follows: Figure 6 As shown in (b), the imaging system before and after correction was analyzed. Figure 6 (a) The white line shows the ratio of phosphorescence intensity in the radial direction of the cold jet. The results are as follows: Figure 6 As shown in (c): Before system correction, the phosphorescence intensity ratio I 425 / I 466 The fluctuation range is 0.115, and the phosphorescence intensity ratio after system correction is I. 425 / I 466 The fluctuation range was 0.025, and the error was reduced by 78%.

[0098] Using the correction method of this invention, the PRUN index of the imaging system response inhomogeneity before and after correction is calculated to evaluate the effect of the correction method on improving the response uniformity of the imaging system. The calculation formula is as follows:

[0099]

[0100] The PRUN decreased from 25.97% before correction to 1.17% after correction, indicating a significant improvement in the inhomogeneity of the imaging system response.

[0101] This embodiment provides a wide-range response correction device for a spectrophotometric laser-induced phosphorescence imaging system, including a processor and a memory; the memory stores a program or instructions, which are loaded and executed by the processor to implement the steps of the wide-range response correction method for the spectrophotometric laser-induced phosphorescence imaging system of this embodiment.

Claims

1. A calibration method for a spectroscopic laser-induced phosphorescence imaging system, characterized in that, include: A light-diffusing plate that fills the entire field of view of the CCD camera is selected as the standard light source; the adjusted beam-splitting laser-induced phosphorescence imaging system is placed in front of the light-diffusing plate so that the light-emitting surface of the light-diffusing plate is located at the focal plane of the imaging system. Set the acquisition frequency, total acquisition time, and N different exposure times, and acquire N sets of grayscale images obtained by the imaging system under different exposure times; For the N sets of grayscale images collected, the average value of each pixel is used to obtain the image grayscale matrix set (Y1Y2...Y1) for each set of grayscale images. N ); For the set of grayscale matrices (Y1 Y2...Y) under N exposure times N The bias correction matrix and gain correction matrix are obtained by linear fitting using the least squares method. Based on the obtained bias correction matrix and gain correction matrix, the original response grayscale matrix obtained under the test state is corrected.

2. The calibration method for a beam-splitting laser-induced phosphorescence imaging system according to claim 1, characterized in that, For the set of grayscale matrices (Y1 Y2...Y) under N exposure times N The steps for obtaining the bias correction matrix and gain correction matrix using linear fitting with the least squares method include: The least squares method was used to analyze the image grayscale matrix set (Y1 Y2...Y...). N The pixel with the highest grayscale value y max Perform linear fitting; Based on the fitting results, determine the bias error and gain coefficient of the ideal response curve; Based on the bias error and gain coefficient of the ideal response curve, determine the image grayscale matrix Y. o Any pixel y i,j The bias error, gain coefficient, and correction factor of the gain coefficient of the response curve, where i is an integer and 1≤i≤m, j is an integer and 1≤j≤n, and o is an integer and 1≤o≤N; Based on the obtained image grayscale matrix Y o Any pixel y i,j The bias error, gain coefficient, and gain coefficient correction factor of the response curve are used to obtain the bias correction matrix and gain correction matrix.

3. The calibration method for a beam-splitting laser-induced phosphorescence imaging system according to claim 2, characterized in that, The steps involve using the least squares method to analyze the image grayscale matrix (Y1 Y2 ... Y...). N The pixel with the highest grayscale value y max Perform a linear fit; the linear fit formula is: In the formula, a max For the response gain coefficient, b max In response to the bias error, r max The linear fit is given by x, which is a constant light source intensity value, and the other variables are: In the formula, x N y represents the exposure time of the Nth grayscale image. maxN This represents the maximum gray value of a pixel in the Nth grayscale matrix.

4. The calibration method for a beam-splitting laser-induced phosphorescence imaging system according to claim 3, characterized in that, The steps involve determining the bias error and gain coefficient of the ideal response curve based on the fitting results, including: Take y maxN This represents the maximum gray value of a pixel in the Nth gray-level matrix and serves as a calibration point. The bias error and gain coefficient of the ideal response curve are determined as follows: b max (y max1 +y max2 +…+y maxN ) / Ankle max (x1+x2+…+x N ) / N fluent max ((y max1 ·x1+y max2 ·x2+...+y maxN ·x N ) / N−(y max1 +y max2 +…+y maxN )·(x1+x2+…+x N ) / N 2 ) / ((x1 2 +x2 2 +…+x N 2 ) / N-(x1+x2+…+x N ) 2 / N 2 ) In the formula, b max The bias error of the ideal response curve; a max The gain coefficient of the ideal response curve; Determine the image grayscale matrix Y o The bias error and gain coefficient of the response curve of any pixel in the curve are as follows: b i,j (y i,j,1 +y i,j,2 +…+y i,j,N ) / Ankle i,j (x1+x2+…+x N ) fluent i,j ((y i,j,1 ·x1+y i,j,2 ·x2+...+y i,j,N ·x N ) / N−(y i,j,1 +y i,j,2 +…+y i,j,N )·(x1+x2+…+x N ) / N 2 ) / ((x1 2 +x2 2 +…+x N 2 ) / N-(x1+x2+…+x N ) 2 / N 2 ) In the formula, b i,j The bias error of the response curve, a i,j The gain coefficient of the response curve, y i,j,N The pixels in the Nth grayscale image; Determine the image grayscale matrix Y o Correction factor c for the gain coefficient of the response curve of any pixel i,j : c i,j =a max / a i,j For the set of grayscale matrices (Y1 Y2...Y) under N exposure times N ), thus obtaining the bias correction matrix B and the gain correction matrix C, where B is b i,j The set of C, where C is c i,j A set of.

5. The calibration method for a beam-splitting laser-induced phosphorescence imaging system according to any one of claims 1-4, characterized in that, The image grayscale matrix set (Y1 Y2...Y...) N Any image grayscale matrix Y in ) o for: In the formula, o is an integer and 1≤o≤N.

6. The method for wide-range response correction of a spectroscopic laser-induced phosphorescence imaging system according to claim 5, characterized in that, In the step of correcting the original response grayscale matrix obtained under test conditions based on the obtained bias correction matrix and gain correction matrix, the correction formula is as follows: Y correction =(Y-B).*C In the formula, Y correction B is the corrected grayscale matrix, C is the bias correction matrix, and Y is the original response grayscale matrix obtained under test conditions.

7. A calibration device for a beam-splitting laser-induced phosphorescence imaging system, comprising a processor and a memory; wherein the memory stores a program or instructions, the program or instructions being loaded and executed by the processor to implement the steps of the calibration method for a beam-splitting laser-induced phosphorescence imaging system as described in any one of claims 1-6.

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