Multi-parameter joint optimization method for space-based infrared detection system for aerial targets

Abstract

The present invention relates to a multi-parameter joint optimization method for a space-based infrared detection system for aerial targets, including: establishing an aerial target infrared characteristic characterization model and a full-link simulation model of a space-based infrared detection system; analyzing the spectral radiation intensity of the aerial target and the background; based on the aerial target infrared characteristic characterization model, statistically analyzing the target detection contrast and detection energy acquisition factors, and determining the preferred detection spectrum; based on the preferred detection spectrum, jointly optimizing the target motion speed limit, earth background limit, and detection sensitivity of the space-based infrared detection system. The present invention realizes the design of an index system for a high-sensitivity detection system for dark and weak aerial targets under complex backgrounds, improves the infrared detection efficiency of aerial targets, and provides a theoretical basis for high-sensitivity detection of aerial targets under complex infrared earth backgrounds and system parameter design.

Description

Technical Field

[0001] The present invention relates to the field of spacecraft payload technology, and in particular to a multi-parameter joint optimization method for a space-based infrared detection system for aerial targets. Background Art

[0002] With the development of technology, aerial targets, such as civil aircraft, are distributed all over the world and are widely used in transportation, reconnaissance and surveillance. As a result, the detection and monitoring of aerial targets has gradually developed into the main research direction. Compared with ground-based and air-based platforms, space-based platforms have the advantages of wide coverage and continuous monitoring of hot spots, making them the main detection method. However, complex earth background clutter, strong atmospheric attenuation and low infrared characteristic design of aerial targets greatly inhibit the detectability of aerial targets. Therefore, studying the spectral radiation characteristics of aerial targets and proposing a space-based infrared detection index system for aerial targets has become a current research hotspot.

[0003] The space-based infrared detection system combines the advantages of both space-based platforms and infrared sensors, and uses multi-band infrared sensors to detect and track targets. It has the advantages of long detection distance, wide coverage, high measurement accuracy, and strong concealment, and has become the main detection method for aerial targets. However, the complex earth background clutter, strong atmospheric attenuation, and low infrared feature design of aerial targets have greatly inhibited the detectability of aerial targets. At present, the research on the optimal detection system parameters for aerial targets has only stayed at the analysis of the impact of a single parameter, and there has been no comprehensive study of the factors that affect the system detection performance and their mutual constraints, including target characteristics, sensor parameters, etc. The detection performance of the space-based infrared detection system for aerial targets needs to be improved. Summary of the invention

[0004] In order to solve the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a multi-parameter joint optimization method for a space-based infrared detection system for aerial targets, a system parameter optimization method with target motion speed limit, earth background limit and detection sensitivity as three major boundaries, realizes the design of an index system for a high-sensitivity detection system for dark and weak aerial targets under complex backgrounds, improves the infrared detection efficiency of aerial targets, and provides a theoretical basis for high-sensitivity detection of aerial targets under complex infrared earth backgrounds and system parameter design.

[0005] To achieve the above-mentioned object of the invention, the present invention provides a multi-parameter joint optimization method for a space-based infrared detection system for aerial targets, comprising the following steps:

[0006] Step S1, establishing an aerial target infrared characteristic characterization model and a full-link simulation model of a space-based infrared detection system;

[0007] Step S2, analyzing the spectral radiation intensity of the aerial target and the background;

[0008] Step S3, based on the infrared characteristic characterization model of the aerial target, statistically analyzing the target detection contrast and detection energy acquisition factors, and determining the preferred detection spectrum;

[0009] Step S4: Based on the preferred detection spectrum, the target motion speed limit, the earth background limit, and the detection sensitivity of the space-based infrared detection system are jointly optimized and designed.

[0010] According to a technical solution of the present invention, in step S1, an infrared characteristic characterization model of an aerial target is constructed based on the infrared radiation characteristics of the aerial target, and the infrared radiation characteristics of the aerial target at least include: infrared thermal radiation intensity of the skin spectrum, reflected radiation of the skin to the sun, and thermal radiation of the tail flame;

[0011] Based on the aerial target infrared characteristic characterization model, background radiation characteristic model, target micro-motion model, and atmospheric transmission model, a full-link simulation model of the space-based infrared detection system is constructed, which takes into account the spatiotemporal differential characteristics of target motion within the integration time and the detector pixel response model.

[0012] According to a technical solution of the present invention, the step S2 specifically includes:

[0013] The aerial target is taken as a point source. After the optical system collects information, the point source finally forms a Gaussian scattering spot on the focal plane, and part of the signal falls on the central pixel of the aerial target. When the aerial target is located at the central pixel, the percentage of the energy of the corresponding spot to the total energy is the energy concentration EE of the optical system. The normalized mapping relationship between the energy concentration of the optical system and the Gaussian distribution point spread function of the point source imaging is expressed as:

[0014]

[0015] Among them, m and n represent the horizontal and vertical coordinates of the distribution points with the centroid of the point source as the origin;

[0016] The radiation information of the aerial target and the background is collected by the detector after the energy of the optical system is gathered, and converted into photoelectrons and stored in the detector integration capacitor. The number of response electrons of the aerial target is N. tar and the background response electron number N back Expressed as:

[0017] N tar =I q,tar ·A opt ·τ atm ·τ opt EE η T int / R 2,

[0018] N back =L q,back ·ifov 2 ·A opt ·τ atm ·τ opt ·η·T int ,

[0019] Among them, I q,tar is the target radiation intensity in the form of photons, A opt is the effective entrance pupil area of ​​the optical system, A opt =πD 2 / 4, D is the optical aperture, τ atm is the atmospheric transmittance, τ opt is the optical efficiency, η is the quantum efficiency, T int is the integration time, R is the target detection distance, ifov is the angular resolution;

[0020] The number of electrons N of the aerial target tar represents the spectral radiation intensity of the aerial target, expressed as the number of response electrons N of the background back represents the spectral radiation intensity of the background.

[0021] According to a technical solution of the present invention, step S3 includes:

[0022] Considering the three factors of earth background radiation characteristics, atmospheric transmittance characteristics and aircraft radiation characteristics, when detecting targets, the background radiation is suppressed, the spectral radiation intensity of aerial targets and background in different spectral bands is analyzed, the spectral radiation characteristic diagram of aerial targets and background is obtained, and the spectral band with stronger target detection contrast is determined as the preferred detection spectral band;

[0023] The detection energy acquisition factors include the skin spectrum infrared thermal radiation intensity and the tail flame thermal radiation.

[0024] According to a technical solution of the present invention, an infrared characteristic characterization model of an aerial target is established, which specifically includes:

[0025] Step S11: The radiation of the skin complies with Planck's radiation law. The spectral radiation emittance of the skin is expressed as:

[0026]

[0027] Among them, the first radiation constant c 1 =2πhc 2 =3.7415×10 4 W cm -2 μm 4 , the second radiation constant c2 =hc / k=1.43879×10 4 μm·K,T skin is the skin temperature;

[0028] The infrared signal strength of the skin of an aerial target is related to the aerodynamic heating effect of the surrounding atmosphere. The average skin temperature T after the aircraft reaches thermal equilibrium is ave Expressed as:

[0029]

[0030] Among them, T atm is the ambient atmospheric temperature of the aircraft; β is the temperature recovery coefficient, which indicates the proportion of kinetic energy actually converted into the increase of gas temperature, and its value range is 0.82~0.84; υ is the specific heat ratio, M a is the flight speed, C is the thermal balance coefficient;

[0031] The infrared thermal radiation intensity of the skin spectrum generated by the aerodynamic heating of the aerial target is skin It is expressed as:

[0032]

[0033] Among them, ε skin is the infrared emissivity of the skin, T ave is the average temperature of the skin, A skin is the projection area from the skin to the detector array;

[0034] Step S12: Divide the tail flame temperature distribution diagram of the aerial target into a P×Q two-dimensional grid, then the infrared radiation intensity I plume The expression is:

[0035]

[0036] Among them, ε plume is the infrared emissivity of the tail flame, A grid is the projected area of ​​each microgrid;

[0037] Step S13: The reflected radiation of the skin to the sun is expressed as:

[0038]

[0039] Among them, τ sun Indicates the atmospheric transmittance from the sun to the target in the sky, T sun represents the solar temperature, r diff Represents the diffuse reflectivity of the skin, A ref Represents the visible area of ​​the skin along the direction of the sun, the radius of the sun R sun =6.9627×10 8m, average distance between the sun and the earth R e-s =1.4960×10 11 m;

[0040] Step S14: Consider the atmospheric transmittance τ of the aerial target reaching the detection system atm (λ) and atmospheric path radiation I path (λ), then the infrared characteristic of the aerial target I aircraft Can be characterized as:

[0041]

[0042] Among them, λ 1 and λ 2 are the starting wavelength and cut-off wavelength of the detection spectrum respectively.

[0043] According to a technical solution of the present invention, step S4 includes:

[0044] The detection signal-to-noise ratio is used to express the air target detection capability and determine the detection sensitivity of the space-based infrared detection system;

[0045] In order to take into account both the target dynamic range and detection sensitivity, the number of detector response electrons cannot exceed 50% of the full well number of electrons during the integration time, and the target flight distance cannot exceed one pixel. The integration time T int Need to meet:

[0046]

[0047] Among them, N full is the full well charge number, S is the size of a single pixel, v tar is the target movement speed;

[0048] Earth background radiance P back Expressed as:

[0049] P back =L q,back ·ifov 2 ·A opt ·τ atm ·τ opt ·η

[0050] The number of image stacking frames is limited by the target movement speed. Therefore, within the target image stacking time, the target movement distance does not exceed the ground resolution of the system, which can be expressed as:

[0051]

[0052] Where GR is the ground resolution, v x and v yare the target motion speeds in the column and row directions respectively, and Fr is the system operating frame rate;

[0053] Based on the preferred detection spectrum, the parameters of the space-based infrared detection system are traversed and optimized considering the two boundary conditions of integration time background limit and target motion speed limit, and the optimal detection angular resolution and achievable detection sensitivity under different detection apertures are analyzed.

[0054] According to a technical solution of the present invention,

[0055] Determine the detection sensitivity of the space-based infrared detection system, including:

[0056] The system noise is divided into signal-correlated quantum shot noise that follows a Poisson distribution Circuit noise that is unrelated to the signal read , then the detection sensitivity NEI is expressed as:

[0057]

[0058] The smaller the NEI value, the higher the sensitivity of the detection system.

[0059] According to a technical solution of the present invention, the detection spectrum is preferably 2.6-2.68 μm, 2.72-2.76 μm or 2.8-2.95 μm.

[0060] According to one aspect of the present invention, there is provided an electronic device, comprising: one or more processors, one or more memories, and one or more computer programs; wherein the processor is connected to the memory, and the one or more computer programs are stored in the memory, and when the electronic device is running, the processor executes the one or more computer programs stored in the memory, so that the electronic device executes a multi-parameter joint optimization method of a space-based infrared detection system for aerial targets as described in any one of the above technical solutions.

[0061] According to one aspect of the present invention, a computer-readable storage medium is provided for storing computer instructions. When the computer instructions are executed by a processor, a multi-parameter joint optimization method of a space-based infrared detection system for aerial targets as described in any one of the above technical solutions is implemented.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] The present invention proposes a multi-parameter joint optimization method for a space-based infrared detection system for aerial targets. By establishing a characterization of the spectral radiation characteristics of the target and the background in a space-based infrared detection scenario, the detection spectrum is preliminarily optimized by comprehensively considering the target detection contrast and the detection energy acquisition factors, and a characterization method for the aerial target detection sensitivity is established. The system parameters are traversed and optimized by considering the two boundary conditions of the background limitation of the integration time and the target movement speed limitation, thereby realizing the optimal design of the detection system parameters under a specific detector.

[0064] Furthermore, the present invention adopts a system parameter optimization method with target motion speed limit, earth background limit and detection sensitivity as three major boundaries, realizes the design of an index system for a high-sensitivity detection system for faint aerial targets under complex backgrounds, improves the infrared detection efficiency of aerial targets, and provides a theoretical basis for high-sensitivity detection of aerial targets under complex infrared earth background and system parameter design. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0066] Figure 1 The overall flow chart of a multi-parameter joint optimization method of a space-based infrared detection system for aerial targets according to one embodiment of the present invention is schematically shown;

[0067] Figure 2 A schematic diagram of an overall flow chart of a multi-parameter joint optimization method for a space-based infrared detection system for aerial targets according to another embodiment of the present invention is shown;

[0068] Figure 3 A schematic diagram of a full-link simulation model of a space-based infrared detection system according to an embodiment of the present invention is schematically shown;

[0069] Figure 4 Schematically showing the temperature distribution characteristics of the tail flame of an aerial target according to one embodiment of the present invention;

[0070] Figure 5 Schematically represents the infrared emissivity of the tail flame of an aerial target according to one embodiment of the present invention;

[0071] Figure 6 A schematic diagram of micro-pixel segmentation according to an embodiment of the present invention is schematically shown;

[0072] Figure 7A schematic diagram of a micro-motion model within an integral time according to an embodiment of the present invention is schematically shown;

[0073] Figure 8 Schematically showing a spectral radiation characteristic diagram of an aerial target and a background according to an embodiment of the present invention;

[0074] Fig. 9 A diagram schematically showing the relationship between angular resolution and detection sensitivity when the detection sensitivity of a multi-frame stacking camera is not considered according to an embodiment of the present invention;

[0075] Fig.10 The figure schematically shows the relationship between angular resolution and detection sensitivity when considering the detection sensitivity of a multi-frame stacking camera according to an embodiment of the present invention. DETAILED DESCRIPTION

[0076] The description of the embodiments of this specification should be combined with the corresponding drawings, which should be considered as part of the complete specification. In the drawings, the shape or thickness of the embodiments may be enlarged and indicated for simplification or convenience. Furthermore, the parts of each structure in the drawings will be described separately. It is worth noting that the elements not shown in the drawings or not described in words are in a form known to ordinary technicians in the relevant technical field.

[0077] The description of the embodiments herein and any reference to directions and orientations are only for the convenience of description and are not to be construed as any limitation on the scope of protection of the present invention. The following description of the preferred embodiments may involve combinations of features, which may exist independently or in combination, and the present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0078] like Figure 1 As shown, a multi-parameter joint optimization method of a space-based infrared detection system for aerial targets of the present invention, first, build a full-link detection simulation model, then analyze the target (aerial target) and background radiation intensity, analyze the target detection contrast based on the aerial target and background radiation intensity, determine the preferred detection spectrum, determine the optimal detection spectrum based on the detection sensitivity, traverse the camera aperture and angular resolution, determine the integration time, and judge again whether the detection sensitivity is optimal. If so, output the multi-parameter joint optimal design result of the detector. If not, re-traverse the camera aperture and angular resolution to determine the integration time.

[0079] like Figures 1 to 8 As shown, a multi-parameter joint optimization method of a space-based infrared detection system for aerial targets of the present invention comprises the following steps:

[0080] Step S1, establishing an aerial target infrared characteristic characterization model and a full-link simulation model of a space-based infrared detection system;

[0081] Compared with high-speed aircraft, the infrared radiation characteristics of aerial targets are weaker, and their radiation intensity is easily affected by many factors such as flight speed, flight status, and tail flame temperature. In the process of space-based infrared detection, the sun angle, flight altitude, and attitude will also affect the radiation intensity at the entrance pupil. By establishing an aerial target infrared characteristic characterization model to simulate the infrared detection process of aerial targets, it is helpful to optimize the parameters of the space-based infrared detection system. The aerial target infrared characteristic characterization model is a room model, and the model schematic diagram is shown in the figure below. Figure 1 shown.

[0082] An infrared characteristic characterization model of an aerial target is constructed based on the infrared radiation characteristics of the aerial target, wherein the infrared radiation characteristics of the aerial target at least include: infrared thermal radiation intensity of the skin spectrum, reflected radiation of the skin to the sun, and thermal radiation of the tail flame;

[0083] Compared with other detection platforms, space-based detection platforms have unique advantages such as early detection, wide-area detection, and continuous tracking. The link of the full-link simulation model of the space-based infrared detection system involves the coupling of multiple physical fields, which not only includes the complex physical effects of the target itself and the surrounding environment, but also includes atmospheric transmission, photoelectric coupling effect, detector sampling and other processes. Therefore, based on the infrared characteristic characterization model of aerial targets, the background radiation characteristic model, the target micro-motion model, and the atmospheric transmission model, the above models can be implemented based on the models in the prior art to construct the full-link simulation model of the space-based infrared detection system that takes into account the spatiotemporal differential characteristics of the target motion within the integration time and the detector pixel response model.

[0084] In the process of establishing the infrared characteristic characterization model of aerial targets, generally speaking, the infrared radiation characteristics of aerial targets can be attributed to the thermal radiation of the skin, the reflected radiation of the skin to the sun, and the thermal radiation of the tail flame. The following aerial targets are explained by faint aircraft.

[0085] Among them, the radiation of the aircraft skin obeys Planck's radiation law, and its infrared radiation intensity is determined by the surface temperature and emissivity.

[0086] Step S11: The radiation of the skin complies with Planck's radiation law. The spectral radiation emittance of the skin is expressed as:

[0087]

[0088] Among them, the first radiation constant c 1 =2πhc 2 =3.7415×10 4 W cm -2 μm 4 , the second radiation constant c 2 =hc / k=1.43879×10 4 μm·K,Tskin is the skin temperature;

[0089] The infrared signal strength of the skin of an aerial target is related to the aerodynamic heating effect of the surrounding atmosphere. The average skin temperature T after the aircraft reaches thermal equilibrium is ave Expressed as:

[0090]

[0091] Among them, T atm is the ambient atmospheric temperature of the aircraft; β is the temperature recovery coefficient, which indicates the proportion of kinetic energy actually converted into the increase of gas temperature, and its value range is 0.82~0.84; υ is the specific heat ratio, M a is the flight speed, C is the thermal balance coefficient;

[0092] The aircraft skin emissivity is related to the coating used on the aircraft surface, and the infrared radiation performance of different aircraft is different. Based on the above analysis of the skin emissivity data, this paper sets the skin emissivity to 0.5, and the skin spectrum infrared thermal radiation intensity I generated by the aerodynamic heating of the aerial target skin It is expressed as:

[0093]

[0094] Among them, ε skin is the infrared emissivity of the skin, T ave is the average temperature of the skin, A skin is the projection area from the skin to the detector array;

[0095] Step S12: The high-temperature tail flame ejected from the aircraft exhaust port is a mixture of various gaseous substances produced when hydrocarbon fuels are burned, including H 2 O、CO 2 and CO, etc. This mixture is the main source of infrared radiation. By establishing a mathematical model of tail flame radiation, the spectral radiation characteristics of the tail flame are mainly determined by the tail flame temperature distribution and the tail flame spectral emissivity. Taking the supersonic tail flame flight state as an example, the length of the aircraft tail flame is related to the altitude and air pressure. Its typical temperature distribution is as follows: Figure 5 The high-temperature tail flame emitted by the aircraft tail nozzle is a selective radiator, and its main emission peaks are in the 2.7μm and 4.3μm spectral bands. These two peak spectral bands are also commonly used to detect faint aircraft. Figure 6 This is the typical infrared emissivity distribution curve of the aircraft tail flame.

[0096] Considering the uneven distribution of tail flame temperature, the tail flame temperature distribution is gridded and then calculated by multi-grid superposition. Therefore, the tail flame temperature distribution map of the aerial target is divided into P×Q two-dimensional grids, and the infrared radiation intensity I plume The expression is:

[0097]

[0098] Among them, ε plume is the infrared emissivity of the tail flame, A grid The expression for the projected area of ​​each microgrid is:

[0099]

[0100] Wherein, L and W represent the length and width of the tail flame respectively;

[0101] Step S13: The reflected radiation of the aircraft fuselage to the sun includes diffuse reflection and specular reflection. Considering the change of the sun's position, the reflected radiation of the skin to the sun is expressed as:

[0102]

[0103] Among them, τ sun Indicates the atmospheric transmittance from the sun to the target in the sky, T sun represents the solar temperature, r diff represents the diffuse reflectivity of the skin, A ref Represents the visible area of ​​the skin along the direction of the sun, the radius of the sun R sun =6.9627×10 8 m, average distance between the sun and the earth R e-s =1.4960×10 11 m;

[0104] Step S14: Consider the atmospheric transmittance τ of the aerial target reaching the detection system atm (λ) and atmospheric path radiation I path (λ), then the infrared characteristic of the aerial target I aircraft Can be characterized as:

[0105]

[0106] Among them, λ 1 and λ 2 are the starting wavelength and cut-off wavelength of the detection spectrum respectively.

[0107] Step S2, analyzing the spectral radiation intensity of the aerial target and the background, specifically includes:

[0108] Since the detection solid angle of the space-based infrared detection system for aerial targets is much smaller than the angular resolution of the system, the aerial target is taken as a point source. The point source forms a Gaussian scattering spot on the focal plane after information collection by the optical system, and only part of the signal falls on the central pixel of the aerial target. When the aerial target is located at the central pixel, the percentage of the energy of the corresponding light spot to the total energy is the energy concentration EE of the optical system. The normalized mapping relationship between the energy concentration of the optical system and the Gaussian distribution point spread function of the point source imaging is expressed as:

[0109]

[0110] Among them, m and n represent the horizontal and vertical coordinates of the distribution points with the center of mass of the point source as the origin;

[0111] Figure 6 To characterize the imaging effect after the optical system PSF is divided into micro-pixels and sampled by different pixels. When the infrared camera accumulates scene energy during the integration time, due to the movement of the target, cross-pixel and target deformation may occur. Therefore, a micro-motion model must be established during the integration time (such as Figure 7 As shown in the figure, the performance of a single pixel of the infrared detection system in acquiring the energy of a moving point target is improved.

[0112] The radiation information of the aerial target and the background is collected by the detector after the energy of the optical system is gathered, and converted into photoelectrons and stored in the detector integration capacitor. The number of response electrons of the aerial target is N. tar and the background response electron number N back Expressed as:

[0113] N tar =I q,tar ·A opt ·τ atm ·τ opt EE η T int / R 2 ,

[0114] N back =L q,back ·ifov 2 ·A opt ·τ atm ·τ opt ·η·T int ,

[0115] Among them, I q,tar is the target radiation intensity in the form of photons, A opt is the effective entrance pupil area of ​​the optical system, A opt =πD 2 / 4, D is the optical aperture, τ atm is the atmospheric transmittance, τopt is the optical efficiency, η is the quantum efficiency, T int is the integration time, R is the target detection distance, ifov is the angular resolution;

[0116] The number of electrons N of the aerial target tar represents the spectral radiation intensity of the aerial target, expressed as the number of response electrons N of the background back represents the spectral radiation intensity of the background.

[0117] Step S3, based on the infrared characteristic characterization model of the aerial target, statistically analyzing the target detection contrast and detection energy acquisition factors, and determining the preferred detection spectrum, including:

[0118] Considering the three factors of the earth's background radiation characteristics, the atmospheric transmittance characteristics and the aircraft radiation characteristics, the background radiation is suppressed during target detection, and the spectral radiation intensity of the aerial target and the background in different spectral bands is analyzed to obtain the spectral radiation characteristic diagram of the aerial target and the background, such as Figure 8 As shown, the spectrum segment with stronger target detection contrast is determined as the preferred detection spectrum segment;

[0119] The detection energy acquisition factors include the skin spectrum infrared thermal radiation intensity and the tail flame thermal radiation.

[0120] Depend on Figure 8 It can be seen that the background radiance of 2.5μm~2.6μm and 3.0μm~3.5μm is too strong, which will limit the integration time of the detection system and is not conducive to the improvement of target detection contrast. The reflected radiation of aerial targets belongs to opportunity detection and cannot be used as the main consideration for spectral optimization. When the skin thermal radiation and tail flame radiation of aerial targets are the main considerations, the spectral bands of 2.6~2.68μm, 2.72~2.76μm and 2.8~2.95μm have strong target detection contrast.

[0121] Step S4: Based on the preferred detection spectrum, jointly optimizing the target motion speed limit, the earth background limit, and the detection sensitivity of the space-based infrared detection system, including:

[0122] The detection signal-to-noise ratio is used to express the air target detection capability and determine the detection sensitivity of the space-based infrared detection system;

[0123] After completing the spectrum optimization, the present invention establishes a system parameter optimization method with the target motion speed limit, the earth background limit, and the detection sensitivity as the boundaries. The target motion speed and the earth background radiance are the main factors that limit the system integration time. Within a certain integration time, in order to take into account both the target dynamic range and the detection sensitivity, the number of detector response electrons cannot exceed 50% of the full well number of electrons, and the target flight distance cannot exceed one pixel, then the integration time Tint Need to meet:

[0124]

[0125] Among them, N full is the full well charge number, S is the size of a single pixel, v tar is the target movement speed;

[0126] Earth background radiance P back Expressed as:

[0127] P back =L q,back ·ifov 2 ·A opt ·τ atm ·τ opt ·η

[0128] Multi-frame superposition can further suppress system noise. The number of image superposition frames is limited by the target movement speed. During the target image superposition time, the target movement distance Num does not exceed the ground resolution of the system, which can be expressed as:

[0129]

[0130] Where GR is the ground resolution, v x and v y are the target motion speeds in the column and row directions respectively, and Fr is the system operating frame rate;

[0131] Based on the preferred detection spectrum, the parameters of the space-based infrared detection system are traversed and optimized considering the two boundary conditions of integration time background limit and target motion speed limit, and the optimal detection angular resolution and achievable detection sensitivity under different detection apertures are analyzed.

[0132] By using short-wave infrared detectors to analyze and calculate, we can traverse different angular resolutions and apertures to obtain the integration time, thereby calculating the detection sensitivity and obtaining the optimal design of system parameters. The short-wave infrared detector can use my country's self-developed 2K×2K short-wave mercury cadmium telluride infrared detector.

[0133] In the process of determining the detection sensitivity of the space-based infrared detection system, the following are specifically included:

[0134] Determine the detection sensitivity of the space-based infrared detection system, including:

[0135] The system noise is divided into signal-correlated quantum shot noise that follows a Poisson distribution Circuit noise that is unrelated to the signal read , then the detection sensitivity NEI is expressed as:

[0136]

[0137] The smaller the NEI value, the higher the sensitivity of the detection system.

[0138] based on Figure 8 It can be seen that the preferred detection spectrum range is 2.6-2.68 μm, 2.72-2.76 μm or 2.8-2.95 μm.

[0139] Select 2.6μm~2.95μm as the main spectrum band for aerial target detection to give an example. The radiation intensity of typical aerial targets X and typical aerial targets Y in the spectrum band of 2.6μm~2.95μm is approximately 25W / sr and 50W / sr. After considering the micro-motion model within the integration time, in order to ensure high-sensitivity detection with a signal-to-noise ratio better than 10, the detection sensitivity needs to be better than 1.7W / sr. Use a short-wave infrared detector to perform analysis and calculation, traverse different angular resolutions and apertures, and obtain the integration time to calculate the detection sensitivity and obtain the optimal design of system parameters. For this example, the camera aperture traverses from 1600mm to 2800mm with a step size of 200mm, and the angular resolution traverses from 0.8μrad to 7μrad with a step size of 0.2μrad. The detection sensitivity with and without considering multi-frame superposition is calculated respectively, and the results are shown as follows Fig. 9 and Fig.10 As shown, it can be seen that:

[0140] 1) The multi-frame superposition method can effectively suppress the noise of the detection system and improve the detection sensitivity. The lower the angular resolution of the optical system, the more obvious the effect of noise suppression through multi-frame superposition. Numerical analysis results show that when detecting with a 2800mm aperture and 7μrad angular resolution, the multi-frame superposition method can suppress the noise to 16.2% before multi-frame superposition, and the detection capability is improved by more than 6 times.

[0141] 2) Comprehensively analyzing the detection sensitivity results of multi-frame superposition and non-superposition, when using a 2800mm aperture and an angular resolution of 1.5μrad, the optimal system detection sensitivity can reach 0.355W / sr. When using a 1600mm aperture and an angular resolution of 2.2μrad, the optimal system detection sensitivity can reach 0.747W / sr. Different detection apertures have different optimal detection angular resolutions. When the background limit integration time and the velocity limit integration time are consistent, the system detection sensitivity reaches the optimal level.

[0142] According to one aspect of the present invention, there is provided an electronic device, comprising: one or more processors, one or more memories, and one or more computer programs; wherein the processor is connected to the memory, and the one or more computer programs are stored in the memory, and when the electronic device is running, the processor executes the one or more computer programs stored in the memory, so that the electronic device executes a multi-parameter joint optimization method of a space-based infrared detection system for aerial targets as described in any one of the above technical solutions.

[0143] According to one aspect of the present invention, a computer-readable storage medium is provided for storing computer instructions. When the computer instructions are executed by a processor, a multi-parameter joint optimization method of a space-based infrared detection system for aerial targets as described in any of the above technical solutions is implemented.

[0144] Computer-readable storage media may include any medium capable of storing or transmitting information. Examples of computer-readable storage media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. Code segments may be downloaded via computer networks such as the Internet, intranets, etc.

[0145] The invention discloses a multi-parameter joint optimization method for a space-based infrared detection system for aerial targets, comprising the following steps: step S1, establishing an aerial target infrared characteristic characterization model and a full-link simulation model of a space-based infrared detection system; step S2, analyzing the spectral radiation intensity of the aerial target and the background; step S3, based on the aerial target infrared characteristic characterization model, statistically analyzing the target detection contrast and detection energy acquisition factors, and determining the preferred detection spectrum; step S4, based on the preferred detection spectrum, jointly optimizing the target motion speed limit, earth background limit, and detection sensitivity of the space-based infrared detection system. The invention establishes a full-link simulation model of space-based infrared detection that considers the spatiotemporal differential characteristics of the aerial target motion within the integration time and the response model within the detector pixel, and comprehensively considers the target detection contrast and detection energy acquisition factors to optimize the detection spectrum by analyzing the spectral radiation intensity of the aerial target and the complex earth background. Finally, referring to the modular detection efficiency evaluation method, the system parameters are traversed and optimized considering the two boundary conditions of the integration time background limit and the target motion speed limit, so as to realize the optimal design of the detection system parameters for a specific photoelectric detector, and provide a theoretical basis for the high-sensitivity detection of aerial targets under a complex infrared earth background and the design of system parameters.

[0146] In addition, it should be noted that the present invention can be provided as a method, an apparatus or a computer program product. Therefore, the embodiments of the present invention can take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code.

[0147] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0148] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, so that a series of operation steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable terminal device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0149] It should also be noted that, in this article, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0150] Finally, it should be noted that the above is a preferred embodiment of the present invention. It should be pointed out that although the preferred embodiment of the present invention has been described, for those skilled in the art, once the basic creative concept of the present invention is known, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. Therefore, the attached claims are intended to be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the embodiments of the present invention.

Claims

1. A multi-parameter joint optimization method for a space-based infrared detection system for aerial targets, characterized in that: The following steps are involved: Step S1, establishing an infrared characteristic characterization model of an aerial target and a full-link simulation model of a space-based infrared detection system, specifically comprising: constructing an infrared characteristic characterization model of an aerial target based on the infrared radiation characteristics of the aerial target, wherein the infrared radiation characteristics of the aerial target at least include: infrared thermal radiation intensity of the skin spectrum, reflected radiation of the skin to the sun, and thermal radiation of the tail flame; Based on the aerial target infrared characteristic characterization model, background radiation characteristic model, target micro-motion model, and atmospheric transmission model, a full-link simulation model of the space-based infrared detection system is constructed that takes into account the spatiotemporal differential characteristics of target motion within the integration time and the detector pixel response model; Step S2, analyzing the spectral radiation intensity of the aerial target and the background; Step S3, based on the infrared characteristic characterization model of the aerial target, statistically analyzing the target detection contrast and detection energy acquisition factors, and determining the detection spectrum, including: Considering the three factors of earth background radiation characteristics, atmospheric transmittance characteristics and aircraft radiation characteristics, the background radiation is suppressed during target detection, and the spectral radiation intensity of aerial targets and backgrounds in different spectral bands is analyzed to obtain the spectral radiation characteristic diagram of aerial targets and backgrounds, and the spectral band with the strongest target detection contrast is determined as the detection spectral band; The detection energy acquisition factors include the skin spectrum infrared thermal radiation intensity and the tail flame thermal radiation; Step S4: Based on the detection spectrum, the target motion speed limit, the earth background limit, and the detection sensitivity of the space-based infrared detection system are jointly optimized and designed.

2. The multi-parameter joint optimization method for a space-based infrared detection system for aerial targets according to claim 1 is characterized in that: The step S2 specifically includes: The aerial target is taken as a point source. After the optical system collects information, the point source finally forms a Gaussian scattering spot on the focal plane, and part of the signal falls on the central pixel of the aerial target. When the aerial target is located at the central pixel, the percentage of the energy of the corresponding spot to the total energy is the energy concentration EE of the optical system. The normalized mapping relationship between the energy concentration of the optical system and the Gaussian distribution point spread function of the point source imaging is expressed as: Among them, m and n represent the horizontal and vertical coordinates of the distribution points with the center of mass of the point source as the origin; The radiation information of the aerial target and the background is collected by the detector after the energy of the optical system is gathered, and converted into photoelectrons and stored in the detector integration capacitor. The number of response electrons of the aerial target is N. tar and the background response electron number N back Expressed as: N tar =I q，tar ·A opt ·t atm ·t opt ·EE·h·T int / R 2 , N back =L q，back ·ifov 2 ·A opt ·t atm ·t opt ·the·T int , Among them, I q，tar is the target radiation intensity in the form of photons, A opt is the effective entrance pupil area of ​​the optical system, A opt =πD 2 / 4, D is the optical aperture, τ atm is the atmospheric transmittance, τ opt is the optical efficiency, η is the quantum efficiency, T int is the integration time, R is the target detection distance, ifov is the angular resolution; The number of electrons N of the aerial target tar represents the spectral radiation intensity of the aerial target, expressed as the number of response electrons N of the background back represents the spectral radiation intensity of the background.

3. The multi-parameter joint optimization method for a space-based infrared detection system for aerial targets according to claim 1 is characterized in that: Establish an infrared characteristic characterization model for aerial targets, including: Step S11: The radiation of the skin complies with Planck's radiation law. The spectral radiation emittance of the skin is expressed as: Among them, the first radiation constant c1=2πhc 2 =3.7415×10 4 W cm -2 μm 4 , the second radiation constant c2=hc / k=1.43879×10 4 μm·K,T skin is the skin temperature; The infrared signal strength of the skin of an aerial target is related to the aerodynamic heating effect of the surrounding atmosphere. The average skin temperature T after the aircraft reaches thermal equilibrium is ave Expressed as: Among them, T atm is the ambient atmospheric temperature of the aircraft; β is the temperature recovery coefficient, which indicates the proportion of kinetic energy actually converted into the increase of gas temperature, and its value range is 0.82~0.84; v is the specific heat ratio, M a is the flight speed, C is the thermal balance coefficient; The infrared thermal radiation intensity of the skin spectrum generated by the aerodynamic heating of the aerial target is skin It is expressed as: Among them, ε skin is the infrared emissivity of the skin, T ave is the average temperature of the skin, A skin is the projection area from the skin to the detector array; Step S12: Divide the tail flame temperature distribution diagram of the aerial target into a P×Q two-dimensional grid, then the infrared radiation intensity I plume The expression is: Among them, ε plume is the infrared emissivity of the tail flame, A grid is the projected area of ​​each microgrid; Step S13: The reflected radiation of the skin to the sun is expressed as: Among them, τ sun Indicates the atmospheric transmittance from the sun to the target in the sky, T sun represents the solar temperature, r diff represents the diffuse reflectivity of the skin, A ref Represents the visible area of ​​the skin along the direction of the sun, the radius of the sun R sun =6.9627×10 8 m, average distance between the sun and the earth R e-s =1.4960×10 11 m; Step S14: Consider the atmospheric transmittance τ of the aerial target reaching the detection system atm (λ) and atmospheric path radiation I path (λ), then the infrared characteristic of the aerial target I aircraft Can be characterized as: Among them, λ1 and λ2 are the starting wavelength and cutoff wavelength of the detection spectrum, respectively.

4. The multi-parameter joint optimization method for a space-based infrared detection system for aerial targets according to claim 2 is characterized in that: The step S4 includes: The detection signal-to-noise ratio is used to express the air target detection capability and determine the detection sensitivity of the space-based infrared detection system; In order to take into account both the target dynamic range and detection sensitivity, the number of detector response electrons cannot exceed 50% of the full well number of electrons during the integration time, and the target flight distance cannot exceed one pixel. The integration time T int Need to meet: Among them, N full is the full well charge number, S is the size of a single pixel, v tar is the target movement speed; Earth background radiance P back Expressed as: P back =L q,back ·ifov 2 ·A opt ·t atm ·t opt ·or The number of image stacking frames is limited by the target movement speed. Therefore, within the target image stacking time, the target movement distance does not exceed the ground resolution of the system, which can be expressed as: Where GR is the ground resolution, v x and v y are the target motion speeds in the column and row directions respectively, and Fr is the system operating frame rate; Based on the detection spectrum, the parameters of the space-based infrared detection system are traversed and optimized considering the two boundary conditions of integration time background limit and target motion speed limit, and the optimal detection angular resolution and achievable detection sensitivity under different detection apertures are analyzed.

5. The multi-parameter joint optimization method for a space-based infrared detection system for aerial targets according to claim 4 is characterized in that: Determine the detection sensitivity of the space-based infrared detection system, including: The system noise is divided into signal-correlated quantum shot noise that follows a Poisson distribution Circuit noise that is unrelated to the signal read , then the detection sensitivity NEI is expressed as: The smaller the NEI value, the higher the sensitivity of the detection system.

6. The multi-parameter joint optimization method for a space-based infrared detection system for aerial targets according to claim 5 is characterized in that: The detection spectrum range is 2.6-2.68 μm, 2.72-2.76 μm or 2.8-2.95 μm.

7. An electronic device, characterized in that: include: One or more processors, one or more memories, and one or more computer programs; wherein the processor is connected to the memory, and the one or more computer programs are stored in the memory. When the electronic device is running, the processor executes the one or more computer programs stored in the memory, so that the electronic device executes the multi-parameter joint optimization method of the space-based infrared detection system for aerial targets as described in any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that: Used to store computer instructions, which, when executed by a processor, implement the multi-parameter joint optimization method for a space-based infrared detection system for aerial targets as described in any one of claims 1 to 6.

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