A focal plane dark background correction method and system for long-wave infrared detector

Abstract

The application provides a focal plane dark background correction method and system of a long-wave infrared detector, temperature of different elements in an imaging system is measured, real dark background of each pixel is obtained, the temperature of the different elements is taken as a variable, polynomial fitting is performed on the real dark background of each pixel, a fitting polynomial is established for each pixel, in real imaging, the temperature of different elements is measured in real time, and is substituted into the fitting polynomial of each pixel to obtain a dark background estimation value of each pixel, a theoretical limit of dark background correction is defined, and a correction effect is quantitatively evaluated, the dark background estimation value is deducted from an original image, and dark background correction of a long-wave infrared imaging system can be realized, the correction method and system are directed to a long-wave infrared spectrum, a theoretical limit and a measurement index of dark background correction are proposed, the correction effect can be quantitatively evaluated, and the correction accuracy is improved. Meanwhile, the correction method can be adapted to different working conditions, and the adaptability of the method is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoelectric detection, in particular to a focal plane dark background correction method and system of a long-wave infrared detector. BACKGROUND

[0002] At present, most of the high-performance long-wave infrared detectors are photovoltaic detectors based on HgCdTe material. HgCdTe is a narrow-band semiconductor material, and the relatively narrow band gap greatly increases the defect-assisted tunneling current and the inter-band direct tunneling current of the device. At the same time, defects are very easy to form in the growth or device junction processing of HgCdTe material. These defects act as coincidence centers in the band gap of the material, increase the Shockley-Read-Hall (SRH) recombination rate, and make the coincidence current increase. At the same time, carriers can tunnel through defects in the band gap, increasing the defect-assisted tunneling current. The above factors make it difficult to suppress the dark current of the HgCdTe detector. In addition, in nature, any object with a temperature higher than absolute zero (-273℃) will produce thermal radiation, and infrared radiation is one of them. The thermal radiation of a room temperature object is concentrated in the long-wave infrared spectrum, so background radiation is another difficulty faced by long-wave infrared detection systems.

[0003] The electrons generated by the dark current and the electrons generated by the target signal are superimposed together and are acquired and read out by the detector, and cannot be distinguished. Therefore, the dark current increases the noise of the device and reduces the dynamic range of the focal plane, and even the dark current component is much larger than the signal charge component. In addition to the dark current, the background radiation fluctuation of the entire imaging system is also an important factor restricting the detection quality of the long-wave infrared spectrum. Usually, the effects of dark current and background radiation cannot be accurately distinguished, so we call the combined effect of the two as "dark background". How to eliminate the influence of the dark background is very important for the long-wave infrared spectrum.

[0004] Prior art solution: the common method for eliminating the dark background of the imaging system is "dark frame correction method" and "dark pixel correction method". The "dark frame correction method" needs to shield the target signal incident energy by covering the entrance pupil of the imaging system with a cold light screen before or after normal imaging, to obtain a frame of dark background information as a dark reference (there are patents to obtain multiple frames for averaging to eliminate the fluctuation noise of the dark background). After removing the cold light screen, the target is normally imaged, and the dark reference is subtracted from the effective signal to achieve dark background correction.

[0005] The "dark pixel correction method" needs to shield part of the infrared focal plane pixels, which do not receive signal energy, and only respond to the dark background (referred to as "dark pixels") to monitor the change of the dark background. By fitting the relationship between the dark pixels and the normal photosensitive pixels, the dark background of all photosensitive pixels is estimated, which is deducted from the effective signal. Some patents propose that for large array image detectors, the dark current shows regional distribution characteristics. Therefore, the dark background correction is performed by using dark pixels at different positions of the focal plane to eliminate the problem of uneven distribution of the dark current of the detector.

[0006] The "dark frame correction method" is usually used for visible light detectors. For the infrared spectrum, especially the long-wave infrared spectrum, the dark background is very sensitive to the change of the focal plane temperature and the surrounding environment temperature. Small temperature changes will cause the dark background to change, and the electronic work will continuously generate heat to cause the focal plane and the environment temperature to rise. Therefore, the dark background of the infrared detector changes continuously over time. The dark background frame obtained before and after imaging cannot accurately reflect the real dark background information at the current imaging time. Using this as a dark reference for correction will bring a large error. At the same time, the additional dark background frame will also cause the frame frequency to be reduced, affecting the imaging frequency.

[0007] The "dark pixel correction method" needs additional dark pixels, i.e. shielding part of the pixels so that they are not sensitive to target radiation. In order to eliminate the non-uniformity of the dark current, sometimes dark pixels need to be set at different positions of the focal plane. Due to the limitation of the process, the number of pixels of the long-wave infrared detector is usually small, and setting dark pixels will waste the already tight focal plane resources. In addition, fitting the dark background of all pixels through limited dark pixels is equivalent to introducing pixel difference noise, and the fluctuation of the dark pixels will affect the accuracy of the dark background correction. At the same time, the dark pixels need to be completely shaded, which also puts higher requirements on the implementation process.

[0008] The existing technologies only give the comparison before and after the dark background correction, and different methods will have certain effects more or less. However, no evaluation standard is given to quantitatively measure the effect of the correction method. SUMMARY

[0009] Therefore, the present application provides a long-wave infrared detector focal plane dark background correction method and system which can quantitatively evaluate the correction effect, in order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0010] One of the purposes of the present application is to provide a long-wave infrared detector focal plane dark background correction method, which comprises the following steps:

[0011] Measuring the temperature of different elements in the imaging system;

[0012] Obtaining the real dark background of each pixel;

[0013] Polynomial fitting is performed on the real dark background of each pixel with the temperature of the different elements as a variable, and a fitting polynomial is established for each pixel;

[0014] In real imaging, the temperature of the different elements is measured in real time, and the fitting polynomial of each pixel is substituted to obtain the estimated value of the dark background of each pixel;

[0015] The theoretical limit of dark background correction is defined, and the correction effect is quantitatively evaluated;

[0016] The estimated value of the dark background is deducted from the original image, and the dark background correction of the long-wave infrared imaging system is realized.

[0017] In some embodiments, in the step of measuring the temperature of the different elements in the imaging system, the temperature of the different elements includes the temperature of the focal plane, the temperature of the optical-mechanical body, and the temperature of the electrical box.

[0018] In some embodiments, in the step of obtaining the real dark background value of each pixel, the following steps are included:

[0019] The long-wave infrared detector is placed in a low-temperature environment, the entrance pupil is shielded, and the target radiation is shielded, and the focal plane is cooled by a refrigerator to obtain the real dark background of each pixel.

[0020] In some embodiments, in the step of polynomial fitting the real dark background of each pixel with the temperature of the different elements as a variable, and establishing a fitting polynomial for each pixel, the following steps are included:

[0021] The fitting method of the polynomial fitting adopts neural network fitting.

[0022] In some embodiments, in the step of defining the theoretical limit of dark background correction and quantitatively evaluating the correction effect, the following steps are included:

[0023] The real dark background is subjected to a moving average to obtain a dark background reference, and the real dark background is subtracted from the dark background reference to eliminate the dark background fluctuation caused by the temperature of the different elements, and the difference result is defined as a noise limit.

[0024] The second object of the present application is to provide a focal plane dark background correction system for a long-wave infrared detector, which comprises:

[0025] A temperature detection unit is configured to measure the temperature of the different elements in the imaging system;

[0026] A real dark background unit is configured to obtain the real dark background of each pixel;

[0027] a polynomial fitting unit for polynomial fitting of the temperature of the different elements as a variable to the real dark background of each pixel to establish a fitting polynomial for each pixel;

[0028] a dark background estimation unit for measuring the temperature of the different elements in real time in real imaging and substituting into the fitting polynomial of each pixel to obtain a dark background estimation value of each pixel;

[0029] an evaluation unit for defining a theoretical limit of dark background correction and quantitatively evaluating the correction effect;

[0030] a correction unit for deducting the dark background estimation value from the original image to realize dark background correction of the long-wave infrared imaging system.

[0031] In some embodiments, the temperature of the different elements includes the focal plane temperature, the light machine main body temperature and the electric box temperature.

[0032] In some embodiments, the real dark background unit is used to obtain the real dark background of each pixel, specifically including:

[0033] The long-wave infrared detector is placed in a low-temperature environment, the entrance pupil is shielded, the target radiation is shielded, the focal plane is cooled by a refrigerator to obtain the real dark background of each pixel.

[0034] In some embodiments, the fitting method of the polynomial fitting adopts neural network fitting, the results of a plurality of fitting models are compared, and the method with the best fitting degree is selected. Each pixel has an independent fitting matrix.

[0035] In some embodiments, the evaluation unit is used to define a theoretical limit of dark background correction and quantitatively evaluate the correction effect, specifically including: performing a sliding average on the real dark background to obtain a dark background reference; and subtracting the real dark background from the dark background reference to eliminate the dark background fluctuation caused by the temperature of the different elements, and the difference result is defined as a noise limit.

[0036] The application adopts the above technical solutions, and has the following beneficial effects:

[0037] The application provides a focal plane dark background correction method and system of a long-wave infrared detector, wherein the temperature of different elements in an imaging system is measured; the real dark background of each pixel is obtained; the temperature of the different elements is taken as a variable, and the real dark background of each pixel is polynomial fitted to establish a fitting polynomial for each pixel; in real-time imaging, the temperature of the different elements is measured in real time, and is substituted into the fitting polynomial of each pixel to obtain a dark background estimation value of each pixel; the theoretical limit of the dark background correction is defined to quantitatively evaluate the correction effect; and the dark background estimation value is deducted from an original image, so that the dark background correction of the long-wave infrared imaging system is realized. The focal plane dark background correction method and system of the long-wave infrared detector provided by the application are for the long-wave infrared spectrum, propose the theoretical limit and the measurement index of the dark background correction, and can quantitatively evaluate the correction effect. Compared with the "dark frame correction method", the error caused by the dark background reference collected at different times is avoided. Compared with the "dark pixel correction method", the setting of the dark pixel is omitted, the focal plane size is fully utilized, the error caused by the non-uniformity between the pixels is avoided, and compared with the prior art which only considers a single factor, the factors affecting the dark background are more comprehensive, and the correction accuracy is improved. Meanwhile, the correction fitting variable can be increased according to different working conditions, and the adaptability of the method is improved. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments of the application or the prior art description. Obviously, the drawings described below are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0039] Figure 1 A step flow chart of a focal plane dark background correction method of a long-wave infrared detector provided by the embodiments of the application.

[0040] Figure 1 (A) is a structure schematic diagram of a focal plane dark background correction system of a long-wave infrared detector provided by the embodiments of the application.

[0041] Figure 2 18000 frame dark background output (measured value) provided by the embodiment 1 of the application.

[0042] Figure 3 18000 frame dark background after the moving average provided by the embodiment 1 of the application.

[0043] Figure 4 Theoretical limit of the dark background correction (noise limit std=3.607) provided by the embodiment 1 of the application.

[0044] Figure 5The corresponding relationship between the dark background and the focal plane temperature provided for Embodiment 1 of the present application.

[0045] Figure 6 The temperature change of different positions of the optical-mechanical main body provided for Embodiment 1 of the present application.

[0046] Figure 7 The temperature change of the electrical box provided for Embodiment 1 of the present application.

[0047] FIG. 8(a) is the dark background residual error (std=8.805) only using the focal plane temperature fitting provided for Embodiment 1 of the present application.

[0048] FIG. 8(b) is the dark background residual error (std=4.168) using the focal plane temperature and the electrical box temperature fitting provided for Embodiment 1 of the present application. DETAILED DESCRIPTION

[0049] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0050] In the description of the present application, it is to be understood that the terms "upper", "lower", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0051] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "plurality" is two or more, unless otherwise specifically limited.

[0052] In order to make the purpose, technical solutions and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with the drawings and embodiments.

[0053] Please refer to Figure 1 The present application provides a focal plane dark background correction method of a long-wave infrared detector, comprising the following steps:

[0054] Step S110: measuring the temperature of different elements in the imaging system.

[0055] In the embodiment, firstly, the changes of different temperature elements, including the focal plane temperature, the temperature of different positions of the optical machine main body and the temperature of the electric box, are accurately measured, the temperature measurement accuracy is 0.001K, and the measurement frequency is consistent with the image frame frequency.

[0056] Secondly, the long-wave infrared imaging system is placed in a vacuum low-temperature tank, the environmental temperature is controlled at about 120K, the focal plane is controlled at about 60K by a Stirling refrigerator, and the electric box (electronic system) is placed outside the low-temperature tank due to the limitation of the temperature of components.

[0057] Thirdly, the cold light screen is used to shield the imaging system entrance pupil, shield the target incident energy, the detector output only includes the dark current and the background radiation, a certain number of dark background images are obtained, and the different temperature values of each dark background frame corresponding to the moment are recorded.

[0058] Step S120: Real dark background of each pixel is obtained.

[0059] In the embodiment, the long-wave infrared detector is placed in a low-temperature environment, the entrance pupil is shielded, the target radiation is shielded, the focal plane is cooled by a refrigerator, and the real dark background of each pixel is obtained.

[0060] Step S130: The temperature of different elements is taken as a variable, and the real dark background of each pixel is polynomial fitted to establish an independent fitting polynomial for each pixel.

[0061] Specifically, the fitting method of the polynomial fitting adopts neural network fitting, a plurality of fitting model structures are compared, the method with the best fitting degree is selected, and each pixel has an independent fitting matrix.

[0062] Step S140: In real imaging, the temperatures of different elements are accurately measured in real time, and are substituted into the fitting polynomial of each pixel, so that the dark background estimation value of each pixel is obtained.

[0063] Step S150: The theoretical limit of dark background correction is defined, and the correction effect is quantitatively evaluated.

[0064] In the embodiment, in the step of defining the theoretical limit of dark background correction and quantitatively evaluating the correction effect, the following steps are specifically included: the real dark background is slidingly averaged to obtain a dark background reference; and the real dark background is subtracted from the dark background reference to eliminate the dark background fluctuation caused by different element temperatures, and the difference result is defined as a noise limit.

[0065] Step S160: The dark background estimation value is deducted from the original image, and the dark background correction of the long-wave infrared imaging system is realized.

[0066] The application provides a focal plane dark background correction method of a long-wave infrared detector, and proposes a theoretical limit and a measurement index of dark background correction for a long-wave infrared spectrum, so that the correction effect can be quantitatively evaluated; compared with a "dark frame correction method", the method avoids errors caused by collecting dark background references at different times; compared with a "dark pixel correction method", the method omits the setting of dark pixels and fully utilizes the size of the focal plane; the method avoids errors caused by non-uniformity between pixels; and compared with the prior art which only considers a single factor, the method contains more comprehensive factors affecting the dark background, and improves the accuracy of correction. Meanwhile, the method can increase variables of correction fitting for different working conditions, and improves the adaptability of the method.

[0067] Referring to Figure 1 (A), the application further provides a focal plane dark background correction system of a long-wave infrared detector, which comprises: a temperature detection unit 110, which is used for measuring the temperature of different elements in an imaging system; a real dark background unit 120, which is used for acquiring the real dark background of each pixel; a polynomial fitting unit 130, which is used for performing polynomial fitting on the real dark background of each pixel by taking the temperature of the different elements as a variable, and establishing a fitting polynomial for each pixel; a dark background estimation unit 140, which is used for measuring the temperature of different elements in real imaging, and substituting the temperature into the fitting polynomial of each pixel to obtain a dark background estimation value of each pixel; an evaluation unit 150, which is used for defining a theoretical limit of dark background correction, and quantitatively evaluating the correction effect; and a correction unit 160, which is used for deducting the dark background estimation value from an original image, so that the dark background correction of the long-wave infrared imaging system can be realized.

[0068] In some embodiments, the real dark background unit 120 is used for acquiring the real dark background of each pixel, and specifically comprises: placing the long-wave infrared detector in a low-temperature environment, shielding the entrance pupil, and shielding target radiation, so that the focal plane is cooled by a refrigerator to acquire the real dark background of different pixels.

[0069] In some embodiments, the evaluation unit 150 is used for defining a theoretical limit of dark background correction, and quantitatively evaluating the correction effect, and specifically comprises: performing sliding average on the real dark background to obtain a dark background reference; and subtracting the real dark background from the dark background reference to eliminate the dark background fluctuation caused by the temperature of different elements, and defining the difference result as a noise limit.

[0070] The focal plane dark background correction system of the long-wave infrared detector provided in the above embodiments of the application can refer to the description in the correction method for a detailed working scheme, which will not be repeated here.

[0071] The long-wave infrared detector focal plane dark background correction system provided in the application is directed to the long-wave infrared spectrum, proposes a theoretical limit and a measurement index of dark background correction, and can quantitatively evaluate the correction effect; compared with the "dark frame correction method", the error caused by collecting dark background references at different times is avoided; compared with the "dark pixel correction method", the setting of dark pixels is omitted, the focal plane size is fully utilized, the error caused by the non-uniformity between pixels is avoided, and compared with the prior art which only considers a single factor, the factors affecting the dark background are more comprehensive, and the correction accuracy is improved. Meanwhile, the variables of correction fitting can be increased for different working conditions, and the adaptability of the method is improved.

[0072] Embodiments

[0073] Here, we combine the flowchart (as shown in Figure 1 ) to describe the technical solutions in detail.

[0074] We use the Stirling cryocooler built in the long-wave infrared detector to cool the focal plane to about 60K, the optical-mechanical main body is placed in a vacuum cryogenic tank, and the temperature in the tank is controlled at about 120K. A cold light screen is used to cover the entrance pupil of the imaging system to avoid target radiation entering the detector, the integration time is set to 2.5ms, and 18000 frames of dark background information are collected, as shown in Figure 2 It can be seen that although the optical-mechanical system and the focal plane are cooled to a very low temperature, the dark background still has a large fluctuation with time.

[0075] First, we define the theoretical limit of dark background correction, and the dark background in Figure 2 is averaged, the dark background of each frame is averaged with the dark background of each of the five frames before and after it, the shot noise is eliminated, and it is used as a dark background reference, as shown in Figure 3 . The difference between the real dark background information and the dark background reference can eliminate the fluctuation of the dark background caused by the change of different temperature elements, and only the shot noise is left, as shown in Figure 4 . We define this difference as the theoretical limit of dark background correction, and use its standard deviation (std) as a quantitative index. Because dark background correction can only eliminate the fluctuation caused by temperature changes, but cannot eliminate white noise (shot noise). After dark background correction, the result is closer to the theoretical limit, indicating that the correction effect is better.

[0076] Next, we use different temperature elements to correct the dark background. First, compare the relationship between the focal plane temperature and the dark background, as shown in Figure 5As shown, the left ordinate is the measured value of the dark background, and the right ordinate is the focal plane temperature, and the measurement accuracy is better than 0.001K. It can be seen that the measured value of the dark background of the pixel is highly consistent with the fluctuation of the focal plane temperature, although the fluctuation of the focal plane temperature is very small, only within 0.04K, but the peak-to-valley coincidence with the dark background is very high. At the same time, it can be found that with the increase of time, the two have a macroscopic deviation, which requires the introduction of other elements for auxiliary correction.

[0077] We set temperature measuring points at different positions of the optical machine body, monitor their temperature changes, as shown in Figure 6 It can be seen that the temperature at different positions remains almost unchanged, and it can be judged that the optical machine body will not cause the fluctuation of the dark background of the detector. Then we measure the temperature of the electric box, as shown in Figure 7 Due to the heat generated by the electronic system, the temperature of the electric box increases with time, and then the dark background of the detector increases. Therefore, when we correct the dark background, we need to consider the electric box temperature as a variable.

[0078] In order to verify the effect of the dark background correction of multiple temperature elements, we use two methods to fit and estimate the dark background respectively: the first method only takes the focal plane temperature as the fitting variable; the second method takes the focal plane temperature and the electric box temperature as the fitting variables. The fitting results are subtracted from the measured value of the dark background, and the correction residual of the two methods is obtained by using the method of defining noise limit, as shown in Figure 8, and the residual std is 8.805 and 4.168 respectively. It can be seen that after using the first method to correct the dark background, there is still a large residual. Using the second method, the correction result is close to the theoretical limit, and has good correction effect.

[0079] The method proposed in the application can also expand the elements contained in the fitting variables according to different situations.

[0080] The technical features of the above-described embodiments can be combined arbitrarily, and in order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0081] The above is only a preferred embodiment of the present application, and only the technical principles of the present application are specifically described, and these descriptions are only for explaining the principles of the present application, and cannot be explained as a limitation on the protection scope of the present application in any way. Based on the explanation here, any modification, equivalent replacement and improvement made within the spirit and principles of the present application, and other specific embodiments of the present application which can be easily thought by those skilled in the art without creative labor, should be included in the protection scope of the present application.

Claims

1. A method for correcting dark background in the focal plane of a long-wave infrared detector, characterized in that: The steps include: Measuring the temperature of different elements in the imaging system; Get the real dark background of each pixel; Taking the temperatures of the different elements as variables, the temperatures of the different elements include the focal plane temperature, the optical engine body temperature, and the electrical box temperature, performing polynomial fitting on the true dark background of each pixel, and establishing a fitting polynomial for each pixel; In real imaging, the temperature of different elements is measured in real time and substituted into the fitting polynomial of each pixel to obtain the estimated dark background value of each pixel; Define the theoretical limit of dark background correction and quantitatively evaluate the correction effect. Specifically, the following steps are performed: take a sliding average of the actual dark background to obtain a dark background reference; subtract the actual dark background from the dark background reference to eliminate dark background fluctuations caused by different element temperatures. The difference result is defined as the noise limit. The dark background correction of the long-wave infrared imaging system can be achieved by deducting the dark background estimation value from the original image.

2. The focal plane dark background correction method of a long-wave infrared detector according to claim 1, characterized in that: The steps of obtaining the true dark background value of each pixel specifically include the following steps: The long-wave infrared detector is placed in a low-temperature environment, the entrance pupil is blocked, and the target radiation is shielded. The focal plane is cooled by a refrigerator to obtain a real dark background for each pixel.

3. The focal plane dark background correction method of a long-wave infrared detector according to claim 1, characterized in that: The temperature of different elements is used as a variable, a polynomial fitting is performed on the true dark background of each pixel, and the steps of establishing a fitting polynomial for each pixel are as follows: The polynomial fitting method adopts neural network fitting.

4. The method for correcting dark background in the focal plane of a long-wave infrared detector according to claim 1, wherein: The steps of defining the theoretical limit of dark background correction and quantitatively evaluating the correction effect include the following steps: Perform a sliding average on the true dark background to obtain a dark background reference; subtract the true dark background from the dark background reference to eliminate dark background fluctuations caused by different element temperatures, and the difference result is defined as the noise limit.

5. A focal plane dark background correction system for a long-wave infrared detector, characterized in that: include: Temperature detection unit: used to measure the temperature of different elements in the imaging system; Real dark background unit: used to obtain the real dark background of each pixel; A polynomial fitting unit is configured to use the temperatures of the different elements as variables, including the focal plane temperature, the optical engine body temperature, and the electrical box temperature, to perform a polynomial fitting on the true dark background of each pixel, and establish a fitting polynomial for each pixel; Dark background estimation unit: used to measure the temperature of different elements in real time during real imaging, and substitute it into the fitting polynomial of each pixel to obtain the dark background estimation value of each pixel; Evaluation unit: used to define the theoretical limit of dark background correction and quantitatively evaluate the correction effect. Specifically, it includes: taking a sliding average of the real dark background to obtain a dark background reference; subtracting the real dark background from the dark background reference to eliminate dark background fluctuations caused by different element temperatures. The difference result is defined as the noise limit; Correction unit: used for deducting the dark background estimation value from the original image, thereby realizing dark background correction of the long-wave infrared imaging system.

6. The focal plane dark background correction system for a long-wave infrared detector according to claim 5, wherein: The temperatures of the different elements include the focal plane temperature, the optical machine body temperature, and the electrical box temperature.

7. The focal plane dark background correction system for a long-wave infrared detector according to claim 5 or 6, characterized in that: The real dark background unit is used to obtain the real dark background of each pixel, specifically including: The long-wave infrared detector is placed in a low-temperature environment, the entrance pupil is blocked, and the target radiation is shielded. The focal plane is cooled by a refrigerator to obtain a real dark background for each pixel.

8. The focal plane dark background correction system for a long-wave infrared detector according to claim 5 or 6, characterized in that: The polynomial fitting method adopts neural network fitting, compares the results of multiple fitting models, and selects the method with the best fitting goodness of fit. Each pixel has an independent fitting matrix.

9. The focal plane dark background correction system for a long-wave infrared detector according to claim 5 or 6, characterized in that: The evaluation unit is used to define the theoretical limit of dark background correction and quantitatively evaluate the correction effect, specifically including: performing a sliding average on the actual dark background to obtain a dark background reference; subtracting the actual dark background from the dark background reference to eliminate dark background fluctuations caused by different element temperatures, and the difference result is defined as the noise limit.

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