Aluminum alloy surface infrared reflection signal suppression method

Abstract

The invention discloses an aluminum alloy surface infrared reflection signal suppression method, which comprises the following steps of: acquiring an infrared reflection polarization image of an infrared heat source on the surface of an aluminum alloy sample by adopting a polarization thermal imaging method according to a polarization theory of light; obtaining the basic polarization characteristics of the infrared reflection polarization image through polarization calculation; extracting reflection signals in the infrared reflection polarization image and omni-directional polarization components of a background area according to the basic polarization characteristics; extracting a complete polarization component in the infrared reflection polarization image according to the reflection signal and the omni-directional polarization component of the background area; reconstructing an infrared reflection polarization image of the surface of the aluminum alloy sample according to the complete polarization component; and evaluating the reconstructed heat maps with different characteristics by using three indexes, namely an intensity mean value, an image standard deviation and a target background contrast ratio. According to the invention, the distinguishing capability of useful signals (defect radiation signals) is improved by suppressing or eliminating interference signals (reflection signals).

Description

Technical Field

[0001] The present invention belongs to the category of infrared thermal imaging detection technology in the field of intelligent manufacturing, and specifically relates to a method for suppressing infrared reflection signals on the surface of aluminum alloys. Background Art

[0002] Aluminum alloy structural components are widely used in the automotive, aviation, and aerospace industries. During their manufacturing and maintenance, they require the use of certain technical means for nondestructive detection and assessment of surface crack defects. Defect detection requires a large number of sensors to collect front-end data. Infrared imaging is one such method. Infrared imaging can reveal subtle textures and defects on part surfaces that are difficult to detect with visible light images. However, the smooth surface of aluminum alloy parts is a good reflector of infrared light, and the numerous infrared emission sources in everyday environments mean that infrared images are severely affected by interference from infrared reflection signals. This problem has, to a certain extent, limited the application of infrared imaging.

[0003] Currently, there are several solutions to this problem:

[0004] One method is to spray black matte paint on the surface of the parts, which reduces the infrared reflectivity of the surface and prevents interference from reflected signals. However, the disadvantage of this method is that while the black matte paint reduces the surface reflectivity, the useful infrared radiation signal is also weakened, resulting in a decrease in detection sensitivity, which is "killing one thousand enemies and losing eight hundred of your own."

[0005] The second approach is to suppress reflected signals optically. There are several specific methods, such as: ① blocking reflected signals in the environment outside the imaging range through optical path design, ② using optical lenses to block reflected infrared rays outside the imaging sensor, or ③ suppressing (eliminating) infrared reflected signals through post-image processing. Regarding reflection suppression, currently, most efforts are focused on improving the performance of infrared imaging sensors to suppress infrared cold reflections. Cold reflection suppression is a hardware technology, and no related patents have been found for suppressing or eliminating infrared reflections from the perspective of infrared image processing. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this paper proposes a method for suppressing infrared reflection signals from aluminum alloy surfaces. This method uses polarized infrared imaging to suppress or eliminate infrared reflection signals from aluminum alloy parts. By suppressing or eliminating infrared reflection signals, the infrared signals radiated by surface cracks or other defects can be indirectly enhanced, thereby improving the ability to detect surface defects. Simply put, the ability to resolve useful signals (radiated by defects) is improved by suppressing or eliminating interfering signals (reflected signals).

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A method for suppressing infrared reflection signals on an aluminum alloy surface comprises the following steps:

[0009] According to the polarization theory of light, the polarization thermal imaging method is used to collect the infrared reflection polarization image of the infrared heat source on the surface of the aluminum alloy sample;

[0010] The basic polarization characteristics of the infrared reflective polarization image are obtained through polarization solution. The basic polarization characteristics include: Stokes vector, polarization angle, and polarization degree.

[0011] Extract the omnidirectional polarization components of the reflected signal and background area in the infrared reflective polarization image based on the basic polarization characteristics;

[0012] Extract the complete polarization component in the infrared reflection polarization image based on the omnidirectional polarization component of the reflected signal and the background area;

[0013] The infrared reflection polarization image of the aluminum alloy sample surface is reconstructed based on the complete polarization component;

[0014] The intensity mean, image standard deviation and target-background contrast are used to evaluate the heatmaps reconstructed from different features.

[0015] Preferably, after the infrared reflection polarization image is collected, it is subtracted from the background heat map without reflection signals to eliminate background infrared noise.

[0016] Preferably, the basic polarization characteristics of the infrared reflective polarization image obtained by polarization solution include:

[0017] ;

[0018] ;

[0019] Among them, Stokes vectors S0, S1, and S2 represent the polarized light intensity at three specific angles, P represents the degree of polarization, and A represents the polarization angle. 、 、 The three polarization angles are 0°, 60°, and 120° respectively, which are obtained by using a thermal imager.

[0020] Preferably, extracting the omnidirectional polarization components of the reflection signal and the background area in the infrared reflection polarization image according to the basic polarization characteristics includes:

[0021] ;

[0022] Where, I represents the total light intensity, I θ Represents the intensity of polarization at any angle.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] To address the problem of infrared specular reflection on metal surfaces, this paper uses polarization thermal imaging, based on the polarization theory of light, to capture polarized images of infrared reflection from an infrared heat source on the surface of an aluminum alloy sample. Polarization calculations are used to obtain the basic polarization characteristics of the original thermal image, including the Stokes vector, polarization angle, and degree of polarization. Furthermore, the omnidirectional polarization component and the complete polarization component of the reflective target and background areas in the thermal image are extracted, and the thermal image of the sample surface is reconstructed using these polarization characteristics. The reconstructed thermal images with different characteristics are evaluated using three metrics: intensity mean, image standard deviation, and target-background contrast. The final results show that the polarization characteristics of the reflective target and background areas differ significantly, and that the reflective target in the thermal image can be enhanced or suppressed using polarization characteristics. Reconstructing the thermal image using the complete polarization component can completely suppress the reflective target, making its infrared reflection intensity lower than the background intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0026] Figure 1 Schematic diagrams of the positional relationship between the polarizer and the polarizer holder at three different polarization angles according to an embodiment of the present invention, wherein (a) a polarization angle of 0°, (b) a polarization angle of 60°, and (c) a polarization angle of 120°;

[0027] Figure 2 Schematic diagrams of the original thermal image captured by the thermal imager according to an embodiment of the present invention before and after subtraction of the background thermal image, wherein (a) is the background thermal image (without a reflection source), (b) is the original thermal image with a reflection source, and (c) is the original thermal image after background subtraction.

[0028] Figure 3 Schematic diagrams of Stokes vector, polarization angle A, and polarization degree P images according to an embodiment of the present invention, including: (a) Stokes parameter S0 imaging, (b) Stokes parameter S1 imaging, (c) Stokes parameter S2 imaging, (d) polarization angle A imaging, (e) polarization degree P imaging, and (f) non-polarized light imaging (reference);

[0029] Figure 4 Schematic diagram showing how the mean and standard deviation of the intensity of the target (reflection source) and background area vary with polarization angle, according to an embodiment of the present invention. (a) Mean (0° to 180°), (b) Standard deviation (0° to 180°).

[0030] Figure 5 Schematic diagram of the optimization results of the optimal polarization component for two different parameters according to an embodiment of the present invention, including (a) the intensity mean optimization result (polarization angle 80°), (b) the target-background contrast optimization result (polarization angle 135°), and (c) the original non-polarized imaging thermal image;

[0031] Figure 6 Schematic diagram of the natural light component and fully polarized component diagrams according to an embodiment of the present invention, where (a) natural light component, (b) fully polarized component (80°), and (c) fully polarized component (170°);

[0032] Figure 7 Schematic diagram of the change of the target-background contrast of the complete polarization component with the polarization angle according to an embodiment of the present invention;

[0033] Figure 8 Schematic diagram of the natural light component and fully polarized component diagrams according to an embodiment of the present invention, where (a) natural light component, (b) fully polarized component (78°), and (c) fully polarized component (120°);

[0034] Figure 9 Schematic diagram of polarized infrared image processing according to an embodiment of the present invention;

[0035] Figure 10 A diagram showing the assembly of a polarizing plate and a polarizing plate holder according to an embodiment of the present invention;

[0036] Figure 11 Schematic diagrams of infrared imaging results at three different polarization angles, 0°, 60°, and 120°, using a polarized infrared thermal imaging system according to an embodiment of the present invention. (a) Infrared imaging without a polarizer, (b) with a polarizer installed and the polarizer angle at 0°, (c) with a polarizer installed and the polarizer angle at 60°, and (d) with a polarizer installed and the polarizer angle at 120°.

[0037] Figure 12 Schematic diagram showing how the mean and standard deviation of the intensity of the target and background areas in a fully polarized component image vary with polarization angle, according to an embodiment of the present invention. (a) Mean intensity (0° to 180°), (b) Standard deviation (0° to 180°). DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Example 1

[0041] This invention is a polarization imaging method, or image processing method, or software technology. It combines two methods: optically suppressing reflected signals (i.e., using optical lenses to block reflected infrared rays from the imaging sensor) and suppressing (eliminating) the infrared reflected signals through post-processing.

[0042] When infrared radiation from the environment strikes the surface of a metal, some of it is absorbed and some is reflected. The surface absorbs infrared radiation of varying polarizations to varying degrees, resulting in varying proportions of light components with different polarizations in the reflected light. Consequently, the reflected light exhibits different polarization characteristics. The polarization characteristics of infrared radiation emitted from a material's surface are determined by Brewster's law, Malus's law, and the Fresnel equation.

[0043] Aiming at the problem of infrared specular reflection on metal surfaces, the present invention provides a method for suppressing infrared reflection signals on aluminum alloy surfaces, comprising the following steps: Figure 9 shown.

[0044] According to the polarization theory of light, the polarization thermal imaging method is used to collect the infrared reflection polarization image of the infrared heat source on the surface of the aluminum alloy sample;

[0045] The basic polarization characteristics of the infrared reflective polarization image are obtained through polarization solution. The basic polarization characteristics include: Stokes vector, polarization angle, and polarization degree.

[0046] Extract the omnidirectional polarization components of the reflected signal and background area in the infrared reflective polarization image based on the basic polarization characteristics;

[0047] Extract the complete polarization component in the infrared reflection polarization image based on the omnidirectional polarization component of the reflected signal and the background area;

[0048] The infrared reflection polarization image of the aluminum alloy sample surface is reconstructed based on the complete polarization component;

[0049] The intensity mean, image standard deviation and target-background contrast are used to evaluate the heatmaps reconstructed from different features.

[0050] In this embodiment, 1) a polarized infrared thermal imaging system is used to collect infrared imaging results at three different polarization angles: 0°, 60°, and 120°. Figure 11 As shown, the polarization angle here is defined as the vertical direction between the transmission direction of the polarizer and the reference direction ( Figure 10 The positional relationship between the polarizer and the polarizer frame at the three polarization angles is as follows: Figure 1 shown.

[0051] 2) After the original image is collected, it is subtracted from the background heat map without reflection signal, which can eliminate most of the background infrared noise. Figure 2 shown.

[0052] 3) After the original image is acquired, the Stokes vector of the sample surface is obtained using formula (1) to perform polarization solution.

[0053] Solve for the Stokes vector of the light beam (i.e. the polarization state of the light beam):

[0054] (1)

[0055] in, 、 、 The three polarization angles are respectively the infrared image intensity (i.e., brightness) at three different polarization angles of 0°, 60°, and 120° acquired by a thermal imager.

[0056] Solving (1) above yields the Stokes vector of the incident light, i.e., the polarization state of the observed target. After obtaining the Stokes vector polarization state, the degree of polarization P and the polarization angle A can be calculated using the following formula:

[0057] (2)

[0058] Stokes vector (S0, S1, S2), polarization degree P, and polarization angle A are the basic features in infrared polarization images. Stokes vectors S0, S1, and S2 represent the intensity of polarized light at three specific angles, which can be directly measured by infrared detection equipment (such as thermal imagers). The linear polarization degree and polarization angle can be obtained by combining and calculating the Stokes parameters. The linear polarization degree is the most essential feature of infrared polarization detection, which reflects the magnitude of polarization and has a value range of 0 to 1. The existence and difference of the linear polarization degree determine the feasibility of infrared polarization detection. The physical meaning of the polarization angle is the angle between the vibration direction of the light wave and the reference direction, which reflects the polarization direction of the polarized light. Generally speaking, the polarization angle parameter of the light wave from the object is an intrinsic information directly related to the reflection and radiation characteristics of the object surface, which can be used to characterize the state characteristics of the target and background. For example Figure 3 shown.

[0059] 3) Omnidirectional polarization component extraction.

[0060] Infrared polarization measurement directly obtains infrared polarization intensity in one or several discrete polarization directions. By adjusting the polarization orientation of the polarizer, multiple measurements can be performed to obtain infrared polarization intensity information in any polarization direction. However, in actual testing, it is impossible to measure infrared polarization intensity information in all polarization directions for a specific test object. Furthermore, the several discrete polarization directions measured may not be the optimal polarization directions for highlighting the target. In this case, how to find the optimal polarization direction? Further polarization decomposition methods are used to calculate the infrared polarization component intensity in any polarization direction. Specifically, after measuring infrared polarization intensity information in several discrete polarization directions, the target's polarization state is decomposed using the aforementioned calculation method to obtain basic polarization parameters such as the target's Stokes vector (S0, S1, S2), degree of polarization P, and polarization angle A. Based on this, the following method is used to obtain polarization intensity information at any polarization angle.

[0061] The infrared rays emitted by most natural and artificial targets are partially polarized light, which is composed of unpolarized light and polarized light. Unpolarized light is also called natural light. After entering the imaging detection device, the infrared radiation of the target scene is converted into an infrared image, and the radiation intensity is converted into the image grayscale value. The corresponding natural light component is recorded as I N , the linearly polarized light component is recorded as I P , when the detector has a linear response and the circular polarization component is ignored, the radiation intensity is decomposed into:

[0062] (3)

[0063] If the polarization component of the radiation intensity I is extracted, according to Malus's law, the polarization component intensity extracted in the polarization direction θ is:

[0064] (4)

[0065] Its natural light composition , the fully polarized component , A is the polarization angle, which is defined as the angle between the polarization direction of the incident light and the reference direction.

[0066] Generally speaking, polarized infrared thermal imaging inspections use an infrared thermal imager to obtain a thermal radiation pattern (also known as a heat map) on the surface of the object being inspected. This pattern reflects the intensity of polarized radiation from the surface. Later in data processing, the heat map is often converted into a grayscale image, where the grayscale value of each pixel corresponds to the infrared radiation intensity of the target or background at that location. For an infrared polarization image acquired under any polarization direction θ, the grayscale value (i.e., infrared intensity value) of any pixel can be expressed as follows:

[0067] (5)

[0068] In formula (5), i and j are the coordinates of the target pixel in the image. is the polarized light intensity of the target pixel point under the polarization direction θ, is the natural light component of the target pixel, is the linear polarized light component of the target pixel, and ω is the pixel noise.

[0069] Combining equations (4) and (5), and the definition of polarization degree , the infrared polarization information model is obtained as follows:

[0070] (6)

[0071] In the infrared polarization information model of formula (6), is the infrared intensity value of the target pixel. The model expresses the infrared intensity information and infrared polarization information (polarization degree, polarization angle) as two multiplied factors, which facilitates the analysis of polarization information and the extraction of polarization features.

[0072] According to the infrared polarization information model of formula (6), for each imaging pixel, without considering noise interference, the polarization intensity The relationship between the total light intensity I, the degree of polarization P and the polarization angle A (that is, the angle with the maximum polarization intensity) is as follows:

[0073] (7)

[0074] Where, is any angle, the polarization intensity I at any angle θ It can be read directly from the grayscale image. If the polarization intensity components of three different polarization directions are obtained for the same scene, the Stokes vector can be obtained and the polarization degree P and polarization angle A can be calculated using formula (5). On this basis, the total light intensity I can be calculated using the above transformation form:

[0075] (8)

[0076] In the above formula, θ1 can be any of the three measured polarization angles (that is, it can be any of 0°, 60°, and 120°). After obtaining basic information such as light intensity I, polarization degree P, and polarization angle A, the polarization state of all pixels in the image is determined, and the intensity I of the polarization component at any angle can be solved using formula (8): θ , and is used for subsequent infrared polarization feature analysis. It should be noted that there will be a small number of outliers in the actual measured data. Some outliers cause the denominator of the analytical expression to be zero or outside the domain of definition, which needs to be corrected.

[0077] In infrared thermal imaging detection, the optimal polarization direction is different for different areas of interest or different evaluation criteria. Taking the polarization direction θ as the independent variable and adopting certain optimization criteria, the infrared polarization intensity information can be optimized. Figure 4 、 Figure 5 shown.

[0078] 4) Complete polarization component decomposition.

[0079] Infrared reflections from metal surfaces are usually partially polarized light, which can be considered as a superposition of natural light components and fully polarized components. Usually, due to the relatively small polarization of the object, the natural light component is much larger than the fully polarized component. However, the natural light component, which accounts for a relatively large proportion, does not have discernment. Due to the differences in the polarization of reflections from different object surfaces, the fully polarized component, which has a smaller component, is the part that has discernment and can reflect the reflective characteristics of the material surface. Therefore, according to formula (4), the fully polarized component in the reflected infrared light is decomposed , we can obtain the most direct material surface reflection polarization characteristics, providing a direct reference for the formulation of surface infrared reflection suppression methods.

[0080] Using the above-mentioned complete polarization component decomposition method, the original polarization image is processed to extract the natural light component and the complete polarization component. The reconstructed complete polarization component image contains polarization angle information, and the polarization angle should be determined according to the specific target during reconstruction. If you want to highlight a certain part of the image, you should reconstruct the image using the polarization angle of the target area. Conversely, if you want to suppress the intensity of a certain part of the image, you should reconstruct the image using the complete polarization component at an angle perpendicular to the polarization angle of the target area. In other words, the complete polarization component of each pixel is used to reconstruct the image.

[0081] Based on the above ideas, the complete polarization component is extracted and reconstructed. Figure 6 shows the reconstruction of the natural light component, the reconstruction of the complete polarization component at an 80° polarization angle, and the reconstruction of the complete polarization component at a 170° polarization angle. As can be seen from the figure, compared with the reconstruction of the natural light component, the reflective target is almost completely suppressed in the reconstruction of the 80° complete polarization component, while the reflective target is still visible in the reconstruction of the 170° complete polarization component. Since the purpose of the present invention is to suppress infrared reflection from the aluminum alloy surface, the reconstruction of the 80° complete polarization component thermal map should be selected in actual detection.

[0082] This paper proposes a method to suppress or eliminate infrared reflection signals from aluminum alloy surfaces through polarized infrared imaging. The final results show that there is a significant difference in polarization characteristics between the infrared reflection signals from the aluminum alloy surface and the background area. The reflection signals in the thermal image can be enhanced or suppressed through polarization characteristics. Among them, the complete suppression of the reflection signal can be achieved by reconstructing the thermal image through the complete polarization component, making its infrared reflection intensity lower than the background intensity. Figure 7 shown.

[0083] Figure 8 shows the reconstruction of the natural light component and the heat map of the complete polarization component reconstruction corresponding to the polarization angles of 120° and 78°. It can be seen from the figure that the reflective target is almost completely suppressed in the reconstruction of the complete polarization component of 120° and 78°. It should be pointed out that the polarization angles of 120° and 78° are both in Figure 12 The region where the mean intensity of the reflective target is lower than the mean background intensity is shown in Figure 2. This result indicates that by fully polarized component decomposition, the interference of natural light is eliminated, and the remaining fully polarized components contain relatively pure polarization information of the reflective target. Whether the ultimate goal is to enhance or suppress reflective targets, selecting the fully polarized component corresponding to the appropriate polarization angle can achieve a more ideal effect by reconstructing the heat map.

[0084] Example 2

[0085] The present invention also provides an aluminum alloy surface infrared reflection signal suppression system, comprising: an acquisition module, a first extraction module, a second extraction module, a third extraction module, a reconstruction module and an evaluation module;

[0086] The acquisition module is used to acquire the infrared reflection polarization image of the infrared heat source on the surface of the aluminum alloy sample using the polarization thermal imaging method based on the polarization theory of light;

[0087] The first extraction module is used to obtain the basic polarization characteristics of the infrared reflective polarization image through polarization solution; wherein the basic polarization characteristics include: Stokes vector, polarization angle, and polarization degree;

[0088] The second extraction module is used to extract the omnidirectional polarization components of the reflection signal and background area in the infrared reflection polarization image based on the basic polarization characteristics;

[0089] The third extraction module is used to extract the complete polarization component in the infrared reflection polarization image based on the omnidirectional polarization component of the reflection signal and the background area;

[0090] The reconstruction module is used to reconstruct the infrared reflection polarization image of the aluminum alloy sample surface according to the complete polarization component;

[0091] The evaluation module is used to evaluate the reconstructed heat maps of different features using three indicators: intensity mean, image standard deviation, and target background contrast.

[0092] In this embodiment, after the infrared reflection polarization image is collected, it is subtracted from the background heat map without reflection signals to eliminate background infrared noise.

[0093] In this embodiment, the basic polarization characteristics of the infrared reflective polarization image obtained through polarization solution include:

[0094] ;

[0095] ;

[0096] Among them, Stokes vectors S0, S1, and S2 represent the polarized light intensity at three specific angles, P represents the degree of polarization, and A represents the polarization angle. 、 、 The three polarization angles are 0°, 60°, and 120° respectively, which are obtained by using a thermal imager.

[0097] Preferably, extracting the omnidirectional polarization components of the reflection signal and the background area in the infrared reflection polarization image according to the basic polarization characteristics includes:

[0098] ;

[0099] Where, I represents the total light intensity, I θ Represents the intensity of polarization at any angle.

[0100] The process of suppressing or eliminating the reflected infrared signal in the infrared image of aluminum alloy parts through polarized infrared imaging is "original image background subtraction - polarization vector solution - omnidirectional polarization component extraction - complete polarization component decomposition". Through this process, the reflected infrared signal in the infrared image can be extracted to the greatest extent and deleted, thereby eliminating (or suppressing to the greatest extent) the infrared reflection signal in the infrared image.

[0101] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for suppressing infrared reflection signals on aluminum alloy surfaces, characterized in that: The following steps are involved: According to the polarization theory of light, the polarization thermal imaging method is used to collect the infrared reflection polarization image of the infrared heat source on the surface of the aluminum alloy sample; The basic polarization characteristics of the infrared reflective polarization image are obtained through polarization solution. The basic polarization characteristics include: Stokes vector, polarization angle, and polarization degree. Extract the omnidirectional polarization components of the reflected signal and background area in the infrared reflective polarization image based on the basic polarization characteristics; Extract the complete polarization component in the infrared reflection polarization image based on the omnidirectional polarization component of the reflected signal and the background area; The infrared reflection polarization image of the aluminum alloy sample surface is reconstructed based on the complete polarization component; The intensity mean, image standard deviation and target-background contrast are used to evaluate the heatmaps reconstructed from different features.

2. The method for suppressing infrared reflection signals on aluminum alloy surfaces according to claim 1, characterized in that: After the infrared reflection polarization image is collected, it is subtracted from the background heat map without reflection signal to eliminate the background infrared noise.

3. The method for suppressing infrared reflection signals on aluminum alloy surfaces according to claim 1, characterized in that: The basic polarization characteristics of infrared reflective polarization images obtained through polarization solution include: ； ； Among them, Stokes vectors S0, S1, and S2 represent the polarized light intensity at three specific angles, P represents the degree of polarization, and A represents the polarization angle. 、 、 The three polarization angles are 0°, 60°, and 120° respectively, which are obtained by using a thermal imager.

4. The method for suppressing infrared reflection signals on aluminum alloy surfaces according to claim 3, characterized in that: According to the basic polarization characteristics, the omnidirectional polarization components of the reflected signal and background area in the infrared reflective polarization image are extracted, including: ； Where, I represents the total light intensity, I θ Represents the intensity of polarization at any angle.

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