A method for correcting image distortion caused by high frame rate optical deflection effect

Abstract

This invention discloses a method for correcting high frame rate optical deflection distortion images, comprising: establishing an ideal initial wavefront model; establishing an optical deflection transmission model; establishing an optical deflection model after light travels through a standard atmospheric environment; establishing an optical deflection model after light travels through an atmospheric wind field; establishing an optical deflection model after light travels through an external flow field of a moving platform; using the ideal initial wavefront as the incident light, obtaining a full-process wavefront distortion model and a full-process optical deflection model; subtracting the ideal initial wavefront model from the full-process wavefront distortion model to obtain a full-process wavefront distortion variable model; subtracting the initial propagation direction of the light wave from the full-process optical deflection model to obtain a full-process optical deflection change model; obtaining a high frame rate image; and using the full-process wavefront distortion variable model and the full-process optical deflection change model to remove negative effects from the high frame rate image to obtain a corrected high frame rate image.

Description

Technical Field

[0001] This invention relates to a method for correcting image distortion caused by high frame rate optical deflection effect, which can be used to improve the image quality of high-speed optical imaging devices located inside a moving platform, and belongs to the field of image correction technology. Background Technology

[0002] The high frame rate optical imaging device is located inside the moving platform and monitors other moving targets through an optical window. When the moving platform flies at high speed in the atmosphere, the complex flow field around its nose undergoes high-frequency changes. These high-frequency changes in the complex flow field cause optical deflection effects, such as target image shift, jitter, and blurring. These optical deflection effects affect the imaging performance of the high frame rate optical imaging device.

[0003] Existing methods for correcting optical refraction distortion primarily focus on improving image quality, neglecting to consider the propagation process of light in complex flow fields, resulting in suboptimal correction. This invention, starting from the relationship between optical refractive index and flight parameters, models the optical refraction effect. Using ray tracing, it calculates the wavefront distortion and Stern ratio caused by aerodynamic flow, further analyzing the image distortion caused by optical refraction in high-frame-rate optical imaging devices, and thus performing image correction. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a high frame rate optical deflection effect distortion image correction method. This method solves the problem that existing optical deflection effect distortion image correction methods do not include the transmission process of light in complex flow field regions in the image correction, resulting in poor image correction effect.

[0005] This invention starts with the relationship between optical refractive index and flight parameters, models the optical deflection effect, and uses ray tracing to calculate wavefront distortion caused by aerodynamic flow. It then analyzes the image distortion caused by optical deflection in high-frame-rate optical imaging devices, and performs image correction accordingly. This solves the problem of poor image correction performance in traditional optical deflection distortion correction methods.

[0006] The technical solution of this invention is: a method for correcting image distortion caused by high frame rate optical deflection effect, comprising:

[0007] Establish an ideal initial wavefront model; using the ideal initial wavefront model as the incident light, establish an optical deflection and transmission model;

[0008] An environmental standard atmospheric transmission model is established to obtain the standard atmospheric refractive index distribution. The standard atmospheric refractive index distribution is then substituted into the light deflection transmission model to obtain the wavefront distortion model and the light deflection model after light passes through the standard environmental atmosphere.

[0009] An atmospheric wind field model is established to obtain the refractive index distribution of the atmospheric wind field. The refractive index distribution of the atmospheric wind field is then substituted into the optical deflection and transmission model to obtain the wavefront distortion model and the optical deflection model after the light passes through the atmospheric wind field.

[0010] A model of the external flow field of the motion platform is established to obtain the refractive index distribution of the external flow field of the motion platform. The refractive index distribution of the external flow field of the motion platform is then substituted into the optical deflection and transmission model to obtain the wavefront distortion model and the optical deflection model after the light passes through the external flow field of the motion platform.

[0011] After the coupled light rays sequentially pass through the standard ambient atmospheric transmission model and the optical deflection model, the light rays pass through the atmospheric wind field transmission model and the optical deflection model, and the light rays pass through the external flow field of the moving platform transmission model and the optical deflection model, the full-process wavefront distortion model and the full-process optical deflection model are obtained. The ideal initial optical wavefront model is subtracted from the full-process wavefront distortion model to obtain the full-process wavefront distortion model. The initial propagation parameters of the light wave are subtracted from the full-process optical deflection model to obtain the full-process optical deflection change model.

[0012] The high-speed imaging equipment located inside the motion platform images ground objects through the motion platform's optical window to obtain high frame rate images. By using the whole-process wavefront distortion model and the whole-process optical deflection change model, the influence of the standard ambient atmosphere, atmospheric wind field, and motion platform flow field on the image in the optical transmission path is removed from the high frame rate image to obtain a corrected high frame rate image.

[0013] The establishment of the ideal initial wavefront includes:

[0014] The light waves emitted by an ideal point light source are spherical waves, and the equiphase surfaces are concentric spheres that gradually expand with increasing distance from the point light source; therefore...

[0015] The wave function of a spherical wave is:

[0016]

[0017] Where v is the phase propagation velocity of the spherical wave along the radial direction of the sphere in the medium; r is the distance from the spherical wave to the central point light source, expressed in polar coordinates; t is the propagation time of the spherical wave in the medium; and B is the amplitude function of the spherical wave, describing how the amplitude changes with time and distance.

[0018] When the wave function is in sine or cosine form, the ideal initial wavefront model is:

[0019]

[0020] A1 is the amplitude at r = 1; k is the wave number; This is the initial phase;

[0021] Convert E(r,t) to E(x,y,z,t) by polar coordinates and Cartesian coordinates.

[0022] The establishment of an optical deflection and transmission model using an ideal initial wavefront model as the incident light includes:

[0023] The combination of the environmental standard atmospheric airflow field, the atmospheric wind field, and the flow field of the moving platform is considered as a flow field with velocity V. com The refractive index is n com A flow field with velocity (x,y,z,t) is formed; an incident ray E(r,t) propagates in an undisturbed flow field with refractive index n0(x,y,z,t) and passes through a flow field with velocity V. com The refractive index is n com For a flow field with coordinates (x, y, z, t), due to the deflection of light rays by various gas movements, the resulting distorted wavefront model E′(x, y, z, t) upon exiting the flow field is:

[0024] E′(x,y,z,t)=exp[imOPL]

[0025]

[0026] Where L is the flow field thickness, i represents the imaginary number, m = 2π / λ is the wave number, λ represents the wavelength of the spherical wave; OPL is the optical length of the light ray through the flow field path, and n com (x,y,z,t) represents the refractive index of the spherical wave in the medium, ρ represents the density of the medium, and K represents the refractive index of the spherical wave in the medium. G-D For Glaston-Dell constant data; (x,y,z) represents the location of the spherical wave propagation, and t represents the spherical wave propagation time;

[0027] The optical deflection transmission model is then:

[0028]

[0029] ε x Let ε be the angle of deflection of the light ray in the x-direction. y Let be the angle of deflection of the light ray in the y-direction.

[0030] The establishment of an environmental standard atmospheric transmission model yields the standard atmospheric refractive index distribution. Using the light deflection transmission model, an optical deflection model is obtained after light has passed through the standard environmental atmosphere, including:

[0031] The environmental standard atmospheric transport model is established as follows:

[0032] Troposphere 0 <h<11km:

[0033] T atom_h (h)=T0-αh

[0034]

[0035] Stratosphere 11 <h<20km:

[0036] T atom_h =216.65K

[0037]

[0038] Among them, T atom_h p atom_h α represents the temperature and pressure of the standard atmosphere, respectively; h is the height calculated from sea level, T0 is the surface temperature, p0 is the surface pressure, α is the annual average temperature lapse rate of 6.5℃ / km, R=287J / (kg·K) is the gas constant, and g is the acceleration due to gravity.

[0039] The density change of standard atmosphere is then:

[0040]

[0041] ρ0 is the density of air at 0℃ and 0.1013 MPa, ρ0 = 1.293 kg / m³. 3 ;

[0042] p indicates the relative humidity of the air; atom_b Let T represent the partial pressure of water vapor in saturated air at temperature T; then the standard atmospheric refractive index distribution is:

[0043] n′ atom_h (h,t)=1+K G-D ρ′ atom_h (h,t)

[0044] Substituting the standard atmospheric refractive index distribution into the wavefront model that produces the distortion, E′(x,y,z,t), we obtain the wavefront distortion caused by environmental standard atmospheric transmission as follows:

[0045]

[0046] Among them, L atom This represents the path length of light in standard ambient air.

[0047] Substituting the standard atmospheric refractive index distribution into the light deflection and transmission model, we obtain the light deflection model after light passes through the standard ambient atmosphere as follows:

[0048]

[0049]

[0050] ε atom_xRepresents the light deflection model in the x - direction after the light passes through the standard ambient atmosphere; ε atom_y Represents the light deflection model in the y - direction after the light passes through the standard ambient atmosphere.

[0051] The establishment of the atmospheric wind field model to obtain the refractive index distribution of the atmospheric wind field, and the use of the light deflection transmission model to obtain the light deflection model after the light passes through the atmospheric wind field, including:

[0052] The atmospheric wind field model includes a standard atmospheric wind field model and an atmospheric turbulence flow field model;

[0053] Establish a standard atmospheric wind field model to obtain the refractive index distribution of the standard atmospheric wind field. The specific process is as follows:

[0054] The standard atmospheric pressure is the sum of the dynamic pressure and the static pressure. The dynamic pressure p v is the pressure caused by the movement of the atmospheric wind field, and the static pressure p h is the standard atmospheric pressure; The standard atmospheric wind field model P wind (x, y, h, t) is:

[0055] P wind (x, y, h, t) = p v +p h (x, y, h, t)

[0056] Then the dynamic pressure p v = 0.5ρV 2 , where V is the atmospheric velocity of the wind field; ρ represents the standard atmospheric density;

[0057] Then the atmospheric density formed by the standard atmospheric wind field is:

[0058]

[0059] The refractive index distribution of the standard atmospheric wind field is:

[0060] n wind (x, y, h, t) = 1 + K G-D ρ wind (x, y, h, t)

[0061] Establish an atmospheric turbulence flow field model to obtain the refractive index distribution of the atmospheric turbulence. The specific process is as follows:

[0062] The atmospheric turbulence flow field model is:

[0063]

[0064] Among them, Γ is the gamma function, 0 < p < 2, κ is the turbulence wave number, is the refractive index structure constant;

[0065] The atmospheric turbulent refractive index distribution is as follows:

[0066]

[0067] in, Represents the refractive index structure constant;

[0068]

[0069] V represents the root mean square wind speed along the vertical path. g This refers to the near-ground wind speed;

[0070] Substituting the standard atmospheric wind refractive index distribution and the atmospheric turbulence refractive index distribution into the wavefront model that produces the distortion, E′(x,y,z,t), we obtain the wavefront distortion caused by atmospheric wind transmission as follows:

[0071]

[0072] L wind L represents the path length of light propagation in an atmospheric wind field; turb This represents the path length of light propagation in atmospheric turbulence.

[0073] Substituting the standard atmospheric wind field refractive index distribution and the atmospheric turbulent refractive index distribution into the light deflection and transmission model, we obtain the light deflection model after light propagates through the atmospheric wind field as follows:

[0074]

[0075] ε win_x This represents a light refraction model in the x-direction after light travels through an atmospheric wind field, ε win_y This represents a light refraction model in the y-direction after light is transmitted through the atmospheric wind field.

[0076] The process involves establishing an external flow field model for the motion platform, obtaining the refractive index distribution of the external flow field, and using a light deflection and transmission model to obtain the light deflection results after the light passes through the external flow field of the motion platform, including:

[0077] A three-dimensional model of a high-speed motion platform is established, and a flow field analysis grid is created around the platform. An external flow field model of the motion platform is established, and the density ρ(x,y,z) at each grid is calculated based on the flight speed, flight altitude, and flight attitude of the motion platform.

[0078] Using the Glaston-Dale formula, calculate the refractive index at each point within the grid:

[0079] n(x,y,z)=K G-D ρ(x,y,z)+1

[0080] Taking any point o in space as the center, the refractive index n at point o is obtained through 8 adjacent grid points. o_obj (x,y,z); then the refractive index distribution of the external flow field of the motion platform is:

[0081]

[0082] Where, n i Let be the refractive index of the space points adjacent to point o, i be the x-coordinate of the space point, and j be the y-coordinate of the space point;

[0083] For a spatial point (x j ,y j ,z j The distance between point O(x,y,z) and point O(x,y,z);

[0084] Substituting the refractive index distribution of the external flow field of the moving platform into the wavefront model that produces the distortion, E′(x,y,z,t), we obtain the wavefront distortion caused by light transmission in the external flow field of the moving platform as follows:

[0085]

[0086] L obj This represents the path length of light propagation in the external flow field of the moving platform;

[0087] Substituting the refractive index distribution of the external flow field of the moving platform into the light deflection and transmission model, we obtain the light deflection model after the light passes through the external flow field of the moving platform as follows:

[0088]

[0089] Where, ε obj_x This represents the light refraction model in the x-direction after light passes through the external flow field of the moving platform, ε obj_y This represents a light refraction model in the y-direction after light passes through the external flow field of the moving platform.

[0090] Using an ideal initial wavefront as the incident light, the wavefront distortion model and optical deflection model are obtained sequentially after transmission through a standard ambient atmosphere, after transmission through an atmospheric wind field, and after transmission through an external flow field of a moving platform. This yields the full-process wavefront distortion model and the full-process optical deflection model. Subtracting the ideal initial wavefront model from the full-process wavefront distortion model yields the full-process wavefront distortion model. Subtracting the initial propagation direction of the light wave from the full-process optical deflection model yields the full-process optical deflection change model. This includes:

[0091] The wavefront distortion model for the entire process is as follows:

[0092] E′(x,y,z,t)=E atom′(h,t)+E win ′(x,y,h,t)+E obj ′(x,y,z,t)

[0093] The whole process wavefront distortion variable model is as follows:

[0094] ΔE(x,y,z,t)=E′(x,y,z,t)-E(x,y,z,t)

[0095] The whole process optical deflection model is as follows:

[0096] ε x =ε atom_x +ε win_x +ε obj_x

[0097] ε y =ε atom_y +ε win_y +ε obj_y

[0098] The initial propagation parameters of the light wave are: ε x_0 ε y_0 ;

[0099] After the entire process of optical deflection, the model for the change in optical deflection over the entire process is as follows:

[0100] Δε x =ε x -ε x_0 , Δε y =ε y -ε y_0 .

[0101] The method utilizes a full-process wavefront distortion model and a full-process optical deflection variation model to remove the influence of standard ambient atmosphere, atmospheric wind field, and moving platform flow field on the image from the optical transmission path, resulting in a corrected high frame rate image, including:

[0102] A high frame rate image is considered as a two-dimensional function, defined as I(x,y);

[0103] The light intensity at a certain point in a high frame rate image without distortion is I. in (x in ,y in The initial incident direction is (θ) in_x θ in_y The wavefront is E(x,y,z,t), and the light rays are not deflected, forming an image at point W on the image plane;

[0104] After the entire transmission process, the change in optical refraction Δε occurs. x , Δε yThe transmission direction becomes (θ) in_x +Δε x θ in_y +Δε y If the wavefront is E′(x,y,z,t), then the light intensity becomes I. out (x out ,y out After the light rays are deflected, an image is formed at point G on the image plane;

[0105] After distortion occurs in a high frame rate image, the intensities of points W and G both change;

[0106] The wavefront variation E′(x,y,z,t)-E(x,y,z,t) and the transmission parameter variation (θ) are calculated. in_x +Δε x θ in_y +Δε y This allows us to obtain the change in light intensity I at a specific point on a high frame rate image. out (x out ,y out )-I in (x in ,y in Finally, the corrected high frame rate image is obtained.

[0107] The advantages of this invention compared to existing technologies are as follows: When a high-frame-rate optical imaging device located inside a motion platform images ground objects using a downward-looking or oblique-downward-looking method, this invention couples and models the effects of standard ambient atmospheric transmission, light transmission through atmospheric wind fields, and light transmission through external flow fields of the motion platform on light refraction. This results in a wavefront distortion model, eliminating the influence of the entire imaging chain process on the high-frame-rate image imaging effect and improving image quality. This also solves the problem of poor image correction results caused by traditional optical refraction effect distortion correction methods in high-speed imaging equipment within motion platforms. Attached Figure Description

[0108] Figure 1 This is a flowchart of a high frame rate optical deflection effect distortion image correction method according to the present invention.

[0109] Figure 2 This is a schematic diagram of optical transmission analysis for a high frame rate optical deflection effect distortion image correction method according to the present invention.

[0110] Figure 3 This is a schematic diagram illustrating the change in photosensitive image plane after optical deflection in a high frame rate optical deflection effect image correction method according to the present invention. Detailed Implementation

[0111] like Figure 1As shown, the present invention provides a method for correcting image distortion caused by high frame rate optical deflection, comprising:

[0112] Establish an ideal initial wavefront model; using the ideal initial wavefront model as the incident light, establish an optical deflection and transmission model;

[0113] An environmental standard atmospheric transmission model is established to obtain the standard atmospheric refractive index distribution. The standard atmospheric refractive index distribution is then substituted into the light deflection transmission model to obtain the wavefront distortion model and the light deflection model after light passes through the standard environmental atmosphere.

[0114] An atmospheric wind field model is established to obtain the refractive index distribution of the atmospheric wind field. The refractive index distribution of the atmospheric wind field is then substituted into the optical deflection and transmission model to obtain the wavefront distortion model and the optical deflection model after the light passes through the atmospheric wind field.

[0115] A model of the external flow field of the motion platform is established to obtain the refractive index distribution of the external flow field of the motion platform. The refractive index distribution of the external flow field of the motion platform is then substituted into the optical deflection and transmission model to obtain the wavefront distortion model and the optical deflection model after the light passes through the external flow field of the motion platform.

[0116] After the coupled light rays sequentially pass through the standard ambient atmospheric transmission model and the optical deflection model, the light rays pass through the atmospheric wind field transmission model and the optical deflection model, and the light rays pass through the external flow field of the moving platform transmission model and the optical deflection model, the full-process wavefront distortion model and the full-process optical deflection model are obtained. The ideal initial optical wavefront model is subtracted from the full-process wavefront distortion model to obtain the full-process wavefront distortion model. The initial propagation parameters of the light wave are subtracted from the full-process optical deflection model to obtain the full-process optical deflection change model.

[0117] The high-speed imaging equipment located inside the motion platform images ground objects through the motion platform's optical window to obtain high frame rate images. By using the whole-process wavefront distortion model and the whole-process optical deflection change model, the influence of the standard ambient atmosphere, atmospheric wind field, and motion platform flow field on the image in the optical transmission path is removed from the high frame rate image to obtain a corrected high frame rate image.

[0118] The establishment of the ideal initial wavefront includes:

[0119] The light waves emitted by an ideal point light source are spherical waves, and the equiphase surfaces are concentric spheres that gradually expand with increasing distance from the point light source; therefore...

[0120] The wave function of a spherical wave is:

[0121]

[0122] Where v is the phase propagation velocity of the spherical wave along the radial direction of the sphere in the medium; r is the distance from the spherical wave to the central point light source, expressed in polar coordinates; t is the propagation time of the spherical wave in the medium; and B is the amplitude function of the spherical wave, describing how the amplitude changes with time and distance.

[0123] When the wave function is in sine or cosine form, the ideal initial wavefront model is:

[0124]

[0125] A1 is the amplitude at r = 1; k is the wave number; This is the initial phase;

[0126] Convert E(r,t) to E(x,y,z,t) by polar coordinates and Cartesian coordinates.

[0127] The establishment of an optical deflection and transmission model using an ideal initial wavefront model as the incident light includes:

[0128] The combination of the environmental standard atmospheric airflow field, the atmospheric wind field, and the flow field of the moving platform is considered as a flow field with velocity V. com The refractive index is n com A flow field with velocity (x,y,z,t) is formed; an incident ray E(r,t) propagates in an undisturbed flow field with refractive index n0(x,y,z,t) and passes through a flow field with velocity V. com The refractive index is n com For a flow field with coordinates (x, y, z, t), due to the deflection of light rays by various gas movements, the resulting distorted wavefront model E′(x, y, z, t) upon exiting the flow field is:

[0129] E′(x,y,z,t)=exp[imOPL]

[0130] OPL=∫0 L n com (x,y,z,t)dy=∫0 L [1+K G-D ρ(x,y,z,t)]dy

[0131] E′(x,y,z,t)=exp[im·K G-D ∫0 L ρ(x,y,z,t)dy]

[0132] Where L is the flow field thickness, i represents the imaginary number, m = 2π / λ is the wave number, λ represents the wavelength of the spherical wave; OPL is the optical length of the light ray through the flow field path, and n com (x,y,z,t) represents the refractive index of the spherical wave in the medium, ρ represents the density of the medium, and K represents the refractive index of the spherical wave in the medium. G-DFor Glaston-Dell constant data; (x,y,z) represents the location of the spherical wave propagation, and t represents the spherical wave propagation time;

[0133] The optical deflection transmission model is then:

[0134]

[0135] ε x Let ε be the angle of deflection of the light ray in the x-direction. y Let be the angle of deflection of the light ray in the y-direction.

[0136] The establishment of an environmental standard atmospheric transmission model yields the standard atmospheric refractive index distribution. Using the light deflection transmission model, an optical deflection model is obtained after light has passed through the standard environmental atmosphere, including:

[0137] The environmental standard atmospheric transport model is established as follows:

[0138] Troposphere 0 <h<11km:

[0139] T atom_h (h)=T0-αh

[0140]

[0141] Stratosphere 11 <h<20km:

[0142] T atom_h =216.65K

[0143]

[0144] Among them, T atom_h p atom_h α represents the temperature and pressure of the standard atmosphere, respectively; h is the height calculated from sea level, T0 is the surface temperature, p0 is the surface pressure, α is the annual average temperature lapse rate of 6.5℃ / km, R=287J / (kg·K) is the gas constant, and g is the acceleration due to gravity.

[0145] The density change of standard atmosphere is then:

[0146]

[0147] ρ0 is the density of air at 0℃ and 0.1013 MPa, ρ0 = 1.293 kg / m³. 3 ;

[0148] p indicates the relative humidity of the air; atom_b Let T represent the partial pressure of water vapor in saturated air at temperature T; then the standard atmospheric refractive index distribution is:

[0149] n′atom_h (h,t)=1+K G-D ρ′ atom_h (h,t)

[0150] Substituting the standard atmospheric refractive index distribution into the wavefront model that produces the distortion, E′(x,y,z,t), we obtain the wavefront distortion caused by environmental standard atmospheric transmission as follows:

[0151]

[0152] Among them, L atom This represents the path length of light in standard ambient air.

[0153] Substituting the standard atmospheric refractive index distribution into the light deflection and transmission model, we obtain the light deflection model after light passes through the standard ambient atmosphere as follows:

[0154]

[0155] ε atom_x This represents a model of light refraction in the x-direction after light travels through a standard ambient atmosphere; ε atom_y This represents a light refraction model in the y-direction after light travels through a standard ambient atmosphere.

[0156] The process involves establishing an atmospheric wind field model to obtain the refractive index distribution of the atmospheric wind field, and using a light deflection and transmission model to obtain the light deflection model after the light has passed through the atmospheric wind field, including:

[0157] The atmospheric wind field model includes a standard atmospheric wind field model and an atmospheric turbulent flow field model;

[0158] A standard atmospheric wind field model was established to obtain the refractive index distribution of the standard atmospheric wind field. The specific process is as follows:

[0159] Standard atmospheric pressure is the sum of dynamic pressure and static pressure, where p is the dynamic pressure. v The static pressure p is the pressure caused by atmospheric wind movement. h Standard atmospheric pressure; Standard atmospheric wind field model P wind (x,y,h,t) is:

[0160] P wind (x,y,h,t)=p v +p h (x,y,h,t)

[0161] Then the dynamic pressure p v =0.5ρV 2 V represents the atmospheric velocity of the wind field; ρ represents the standard atmospheric density.

[0162] The atmospheric density formed by the standard atmospheric wind field is:

[0163]

[0164] The refractive index distribution of the standard atmospheric wind field is as follows:

[0165] n wind (x, y, h, t) = 1 + K G-D ρ wind (x, y, h, t)

[0166] Establish an atmospheric turbulence flow field model to obtain the refractive index distribution of atmospheric turbulence. The specific process is as follows:

[0167] The atmospheric turbulence flow field model is:

[0168]

[0169] where Γ is the gamma function, 0 < p < 2, κ is the turbulence wave number, is the refractive index structure constant;

[0170] The refractive index distribution of atmospheric turbulence is:

[0171]

[0172] where, represents the refractive index structure constant;

[0173]

[0174] represents the root mean square vertical path wind speed, V g is the near - surface wind speed;

[0175] Substitute the refractive index distribution of the standard atmospheric wind field and the refractive index distribution of atmospheric turbulence into the wavefront model with distortion E′(x, y, z, t) to obtain the wavefront distortion caused by the transmission of the atmospheric wind field as:

[0176]

[0177] L wind represents the propagation path length of light in the atmospheric wind field; L turb represents the propagation path length of light in atmospheric turbulence;

[0178] Substitute the refractive index distribution of the standard atmospheric wind field and the refractive index distribution of atmospheric turbulence into the light deflection transmission model to obtain the light deflection model after the light passes through the atmospheric wind field transmission as:

[0179]

[0180] ε win_x represents the light deflection model in the x - direction after the light passes through the atmospheric wind field transmission, ε win_yThis represents a light refraction model in the y-direction after light is transmitted through the atmospheric wind field.

[0181] The process involves establishing an external flow field model for the motion platform, obtaining the refractive index distribution of the external flow field, and using a light deflection and transmission model to obtain the light deflection results after the light passes through the external flow field of the motion platform, including:

[0182] A three-dimensional model of a high-speed motion platform is established, and a flow field analysis grid is created around the platform. An external flow field model of the motion platform is established, and the density ρ(x,y,z) at each grid is calculated based on the flight speed, flight altitude, and flight attitude of the motion platform.

[0183] Using the Glaston-Dale formula, calculate the refractive index at each point within the grid:

[0184] n(x,y,z)=K G-D ρ(x,y,z)+1

[0185] Taking any point o in space as the center, the refractive index n at point o is obtained through 8 adjacent grid points. o_obj (x,y,z); then the refractive index distribution of the external flow field of the motion platform is:

[0186]

[0187] Where, n i Let be the refractive index of the space points adjacent to point o, i be the x-coordinate of the space point, and j be the y-coordinate of the space point;

[0188] For a spatial point (x j ,y j ,z j The distance between point O(x,y,z) and point O(x,y,z);

[0189] Substituting the refractive index distribution of the external flow field of the moving platform into the wavefront model that produces the distortion, E′(x,y,z,t), we obtain the wavefront distortion caused by light transmission in the external flow field of the moving platform as follows:

[0190]

[0191] L obj This represents the path length of light propagation in the external flow field of the moving platform;

[0192] Substituting the refractive index distribution of the external flow field of the moving platform into the light deflection and transmission model, we obtain the light deflection model after the light passes through the external flow field of the moving platform as follows:

[0193]

[0194] Where, ε obj_xThis represents the light refraction model in the x-direction after light passes through the external flow field of the moving platform, ε obj_y This represents a light refraction model in the y-direction after light passes through the external flow field of the moving platform.

[0195] Using an ideal initial wavefront as the incident light, the wavefront distortion model and optical deflection model are obtained sequentially after transmission through a standard ambient atmosphere, after transmission through an atmospheric wind field, and after transmission through an external flow field of a moving platform. This yields the full-process wavefront distortion model and the full-process optical deflection model. Subtracting the ideal initial wavefront model from the full-process wavefront distortion model yields the full-process wavefront distortion variable model. Subtracting the initial propagation direction of the light wave from the full-process optical deflection model yields the full-process optical deflection change model, including:

[0196] The wavefront distortion model for the entire process is as follows:

[0197] E′(x,y,z,t)=E atom v(h,t)+E win ′(x,y,h,t)+E obj ′(x,y,z,t)

[0198] The whole process wavefront distortion variable model is as follows:

[0199] ΔE(x,y,z,t)=E′(x,y,z,t)-E(x,y,z,t)

[0200] The whole process optical deflection model is as follows:

[0201] ε x =ε atom_x +ε win_x +ε obj_x

[0202] ε y =ε atom_y +ε win_y +ε obj_y

[0203] The initial propagation parameters of the light wave are: ε x_0 ε y_0 ;

[0204] After the entire process of optical deflection, the model for the change in optical deflection over the entire process is as follows:

[0205] Δε x =ε x -ε x_0 , Δε y =ε y -ε y_0 .

[0206] The method utilizes a full-process wavefront distortion model and a full-process optical deflection variation model to remove the influence of standard ambient atmosphere, atmospheric wind field, and moving platform flow field on the image from the optical transmission path, resulting in a corrected high frame rate image, including:

[0207] A high frame rate image is considered as a two-dimensional function, defined as I(x,y);

[0208] The light intensity at a certain point in a high frame rate image without distortion is I. in (x in ,y in The initial incident direction is (θ) in_x θ in_y The wavefront is E(x,y,z,t), and the light rays are not deflected, forming an image at point W on the image plane;

[0209] After the entire transmission process, the change in optical refraction Δε occurs. x , Δε y The transmission direction becomes (θ) in_x +Δε x θ in_y +Δε y If the wavefront is E′(x,y,z,t), then the light intensity becomes I. out (x out ,y out After the light rays are deflected, an image is formed at point G on the image plane;

[0210] After distortion occurs in a high frame rate image, the intensities of points W and G both change;

[0211] The wavefront variation E′(x,y,z,t)-E(x,y,z,t) and the transmission parameter variation (θ) are calculated. in_x +Δε x θ in_y +Δε y This allows us to obtain the change in light intensity I at a specific point on a high frame rate image. out (x out ,y out )-I in (x in ,y in Finally, the corrected high frame rate image is obtained.

[0212] like Figure 2 As shown, this invention uses a downward-looking or oblique downward-looking method to image ground features. The light intensity at a certain point is I. in (x in ,y in The initial incident direction is θ inThe wavefront is E(x,y,z,t), named ray 0. Ray 1 represents the propagation of ray 0 in the ambient atmosphere, ray 2 represents the propagation of ray 1 in atmospheric turbulence, ray 3 represents the propagation of ray 2 in the atmospheric wind field, ray 4 represents the propagation of ray 0 in the ambient atmosphere, and ray 5 represents the propagation of ray 4 in the external flow field of the moving platform. Ambient atmospheric propagation exists throughout the entire propagation process, while atmospheric turbulence propagation and atmospheric wind field propagation exist within the same altitude range.

[0213] like Figure 3 As shown, the light intensity at a certain point is I. in (x in ,y in The initial incident direction is θ in The wavefront is E(x,y,z,t), and after passing through the transmission path, it is deflected by Δε. x , Δε y The light intensity becomes I out (x out ,y out The transmission direction changes to θ in_x +Δε x ,θ in_y +Δε y The wavefront is E′(x,y,z,t). The incident light ray, without deflection, images at point W on the image plane; after deflection, it images at point G on the image plane; at this point, the intensities at both points W and G change. The wavefront change E′(x,y,z,t)-E(x,y,z,t) and intensity change I obtained through this invention are... out (x out ,y out )-I in (x in ,y in This allows analysis of the effects of standard ambient atmosphere, atmospheric wind field, and moving platform flow field on light deflection in the light transmission path. By removing these effects from the high frame rate image, the corrected high frame rate image can be obtained.

[0214] The motion platform of this invention can be a high-speed motion platform or a low-speed motion platform.

[0215] The optical transmission process described in this invention analyzes the intensity effect caused by light refraction, without elaborating on the effects of scattering, absorption, etc., on intensity during optical transmission. Mature scattering and absorption analysis methods used in optical transmission can be employed to obtain the effects of scattering and absorption on intensity, and these effects can be analyzed together with the intensity effect caused by light refraction.

[0216] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make possible variations and modifications to the technical solutions of the present invention using the disclosed methods and techniques without departing from the spirit and scope of the invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall fall within the protection scope of the present invention. Where there is no conflict, the embodiments of this application and the technical features thereof can be combined with each other.

[0217] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for correcting image distortion caused by high frame rate optical deflection effect, characterized in that, include: Establish an ideal initial wavefront model; using the ideal initial wavefront model as the incident light, establish an optical deflection and transmission model; An environmental standard atmospheric transmission model is established to obtain the standard atmospheric refractive index distribution. The standard atmospheric refractive index distribution is then substituted into the light deflection transmission model to obtain the wavefront distortion model and the light deflection model after light passes through the standard environmental atmosphere. An atmospheric wind field model is established to obtain the refractive index distribution of the atmospheric wind field. The refractive index distribution of the atmospheric wind field is then substituted into the optical deflection and transmission model to obtain the wavefront distortion model and the optical deflection model after the light passes through the atmospheric wind field. A model of the external flow field of the motion platform is established to obtain the refractive index distribution of the external flow field of the motion platform. The refractive index distribution of the external flow field of the motion platform is then substituted into the optical deflection and transmission model to obtain the wavefront distortion model and the optical deflection model after the light passes through the external flow field of the motion platform. Using an ideal initial wavefront as the incident light, the wavefront distortion model and optical deflection model are obtained sequentially after the light passes through the standard ambient atmospheric transmission model, the wavefront distortion model and optical deflection model after the light passes through the atmospheric wind field transmission model, and the wavefront distortion model and optical deflection model after the light passes through the external flow field of the moving platform transmission model. The full-process wavefront distortion model and the full-process optical deflection model are then obtained. Subtracting the ideal initial wavefront model from the full-process wavefront distortion model yields the full-process wavefront distortion model. Subtracting the initial propagation direction of the light wave from the full-process optical deflection model yields the full-process optical deflection change model. The high-speed imaging equipment located inside the motion platform images ground features through the motion platform's light window, obtaining high frame rate images; By using the whole-process wavefront distortion model and the whole-process optical deflection change model, the influence of standard ambient atmosphere, atmospheric wind field and moving platform flow field on the image in the optical transmission path is removed from the high frame rate image to obtain the corrected high frame rate image.

2. The method for correcting image distortion caused by high frame rate optical deflection effect according to claim 1, characterized in that, The establishment of the ideal initial wavefront includes: The light waves emitted by an ideal point light source are spherical waves, and the equiphase surfaces are concentric spheres that gradually expand with increasing distance from the point light source; therefore... The wave function of a spherical wave is: Where v is the phase propagation velocity of the spherical wave along the radial direction of the sphere in the medium; r is the distance from the spherical wave to the central point light source, expressed in polar coordinates; t is the propagation time of the spherical wave in the medium; and B is the amplitude function of the spherical wave, describing how the amplitude changes with time and distance. When the wave function is in sine or cosine form, the ideal initial wavefront model is: A1 is the amplitude at r = 1; k is the wave number; This is the initial phase; Convert E(r,t) to E(x,y,z,t) by polar coordinates and Cartesian coordinates.

3. The method for correcting image distortion caused by high frame rate optical deflection effect according to claim 2, characterized in that, The establishment of an optical deflection and transmission model using an ideal initial wavefront model as the incident light includes: The combination of the environmental standard atmospheric airflow field, the atmospheric wind field, and the flow field of the moving platform is considered as a flow field with velocity V. com The refractive index is n com A flow field with velocity (x,y,z,t) is formed; an incident ray E(r,t) propagates in an undisturbed flow field with refractive index n0(x,y,z,t) and passes through a flow field with velocity V. com The refractive index is n com For a flow field with coordinates (x, y, z, t), due to the deflection of light rays by various gas movements, the resulting distorted wavefront model E′(x, y, z, t) upon exiting the flow field is: E′(x,y,z,t)=exp[imOPL] Where L is the flow field thickness, i represents the imaginary number, m = 2π / λ is the wave number, λ represents the wavelength of the spherical wave; OPL is the optical length of the light ray through the flow field path, and n com (x,y,z,t) represents the refractive index of the spherical wave in the medium, ρ represents the density of the medium, and K represents the refractive index of the spherical wave in the medium. G-D For Glaston-Dell constant data; (x,y,z) represents the location of the spherical wave propagation, and t represents the spherical wave propagation time; The optical deflection transmission model is then: ε x Let ε be the angle of deflection of the light ray in the x-direction. y Let be the angle of deflection of the light ray in the y-direction.

4. The method for correcting image distortion caused by high frame rate optical deflection effect according to claim 3, characterized in that, The establishment of an environmental standard atmospheric transmission model yields the standard atmospheric refractive index distribution. Using the light deflection transmission model, an optical deflection model is obtained after light has passed through the standard environmental atmosphere, including: The environmental standard atmospheric transport model is established as follows: Troposphere 0 <h<11km: T atom_h (h)=T0-αh Stratosphere 11 <h<20km: T atom_h =216.65K Among them, T atom_h p atom_h α represents the temperature and pressure of the standard atmosphere, respectively; h is the height calculated from sea level, T0 is the surface temperature, p0 is the surface pressure, α is the annual average temperature lapse rate of 6.5℃ / km, R is the gas constant, and g is the gravitational acceleration. The density change of standard atmosphere is then: ρ0 is the density of air at 0℃ and 0.1013 MPa. p indicates the relative humidity of the air; atom_b Let T represent the partial pressure of water vapor in saturated air at temperature T; then the standard atmospheric refractive index distribution is: n′ atom_h (h,t)=1+K G-D ρ′ atom_h (h,t) Substituting the standard atmospheric refractive index distribution into the wavefront model that produces the distortion, E′(x,y,z,t), we obtain the wavefront distortion caused by environmental standard atmospheric transmission as follows: Among them, L atom This represents the path length of light in standard ambient air. Substituting the standard atmospheric refractive index distribution into the light deflection and transmission model, we obtain the light deflection model after light passes through the standard ambient atmosphere as follows: ε atom_x This represents a model of light refraction in the x-direction after light travels through a standard ambient atmosphere; ε atom_y This represents a light refraction model in the y-direction after light travels through a standard ambient atmosphere.

5. The method for correcting high frame rate optical deflection distortion images according to claim 4, characterized in that, The process involves establishing an atmospheric wind field model to obtain the refractive index distribution of the atmospheric wind field, and using a light deflection and transmission model to obtain the light deflection model after the light has passed through the atmospheric wind field, including: The atmospheric wind field model includes a standard atmospheric wind field model and an atmospheric turbulent flow field model; A standard atmospheric wind field model was established to obtain the refractive index distribution of the standard atmospheric wind field. The specific process is as follows: Standard atmospheric pressure is the sum of dynamic pressure and static pressure, where p is the dynamic pressure. v The static pressure p is the pressure caused by atmospheric wind movement. h Standard atmospheric pressure; Standard atmospheric wind field model P wind (x,y,h,t) is: P wind (x,y,h,t)=p v +p h (x,y,h,t) Then dynamic pressure p v =0.5ρV 2 V represents the atmospheric velocity of the wind field; ρ represents the standard atmospheric density. The atmospheric density formed by the standard atmospheric wind field is: The refractive index distribution of the standard atmospheric wind field is as follows: n wind (x,y,h,t)=1+K G-D ρ wind (x,y,h,t) An atmospheric turbulent flow field model was established to obtain the atmospheric turbulent refractive index distribution. The specific process is as follows: The atmospheric turbulent flow field model is as follows: where Γ is the gamma function, 0 < p < 2, κ is the turbulence wave number, and is the refractive index structure constant; The atmospheric turbulent refractive index distribution is as follows: in, V represents the refractive index structure constant; RMS This represents the root mean square wind speed along the vertical path. Substituting the standard atmospheric wind refractive index distribution and the atmospheric turbulence refractive index distribution into the wavefront model that produces the distortion, E′(x,y,z,t), we obtain the wavefront distortion caused by atmospheric wind transmission as follows: L wind L represents the path length of light propagation in an atmospheric wind field; turb This represents the path length of light propagation in atmospheric turbulence. Substituting the standard atmospheric wind field refractive index distribution and the atmospheric turbulent refractive index distribution into the light deflection and transmission model, we obtain the light deflection model after light propagates through the atmospheric wind field as follows: ε win_x This represents a light refraction model in the x-direction after light travels through an atmospheric wind field, ε win_y This represents a light refraction model in the y-direction after light is transmitted through the atmospheric wind field.

6. The method for correcting high frame rate optical deflection distortion images according to claim 5, characterized in that, The process involves establishing an external flow field model for the motion platform, obtaining the refractive index distribution of the external flow field, and using a light deflection and transmission model to obtain the light deflection results after the light passes through the external flow field of the motion platform, including: A three-dimensional model of a high-speed motion platform is established, and a flow field analysis grid is created around the platform. An external flow field model of the motion platform is established, and the density ρ(x,y,z) at each grid is calculated based on the flight speed, flight altitude, and flight attitude of the motion platform. Using the Glaston-Dale formula, calculate the refractive index at each point within the grid: n(x,y,z)=K G-D ρ(x,y,z)+1 Taking any point o in space as the center, the refractive index n at point o is obtained through 8 adjacent grid points. o_obj (x,y,z); then the refractive index distribution of the external flow field of the motion platform is: Where, n i Let be the refractive index of the space points adjacent to point o, i be the x-coordinate of the space point, and j be the y-coordinate of the space point; For a spatial point (x j ,y j ,z j The distance between point O(x,y,z) and point O(x,y,z); Substituting the refractive index distribution of the external flow field of the moving platform into the wavefront model that produces the distortion, E′(x,y,z,t), we obtain the wavefront distortion caused by light transmission in the external flow field of the moving platform as follows: L obj This represents the path length of light propagation in the external flow field of the moving platform; Substituting the refractive index distribution of the external flow field of the moving platform into the light deflection and transmission model, we obtain the light deflection model after the light passes through the external flow field of the moving platform as follows: In the formula, ε obj_x This represents the light refraction model in the x-direction after light passes through the external flow field of the moving platform, ε obj_y This represents a light refraction model in the y-direction after light passes through the external flow field of the moving platform.

7. The method for correcting high frame rate optical deflection distortion images according to claim 6, characterized in that, The process involves taking an ideal initial wavefront as the incident light, and then sequentially passing the light through a standard atmospheric transmission model and a light deflection model, followed by a wavefront distortion model and a light deflection model after transmission through an atmospheric wind field, and finally a wavefront distortion model and a light deflection model after transmission through an external flow field of a moving platform. This process yields a complete wavefront distortion model and a complete light deflection model. Subtracting the ideal initial wavefront model from the complete wavefront distortion model yields the complete wavefront distortion model. Subtracting the initial propagation direction of the light wave from the overall optical deflection model yields the overall optical deflection variation model, which includes: The wavefront distortion model for the entire process is as follows: E′(x,y,z,t)=E atom ′(h,t)+E win ′(x,y,h,t)+E obj ′(x,y,z,t) The whole process wavefront distortion variable model is as follows: ΔE(x,y,z,t)=E′(x,y,z,t)-E(x,y,z,t) The whole process optical deflection model is as follows: e x =e atom_x +e win_x +e obj_x e y =e atom_y +e win_y +e obj_y The initial propagation parameters of the light wave are: ε x_0 ε y_0 ; After the entire process of optical deflection, the model for the change in optical deflection over the entire process is as follows: No x =e x -e x_0 、No y =e y -e y_0 。 8. The method for correcting high frame rate optical deflection distortion images according to claim 7, characterized in that, The method utilizes a full-process wavefront distortion model and a full-process optical deflection variation model to remove the influence of standard ambient atmosphere, atmospheric wind field, and moving platform flow field on the image from the optical transmission path, resulting in a corrected high frame rate image, including: A high frame rate image is considered as a two-dimensional function, defined as I(x,y); The light intensity at a certain point in a high frame rate image without distortion is I. in (x in ,y in The initial incident direction is (θ) in_x θ in_y The wavefront is E(x,y,z,t), and the light rays are not deflected, forming an image at point W on the image plane; After the entire transmission process, the change in optical refraction Δε occurs. x , Δε y The transmission direction becomes (θ) in_x +Δε x θ in_y +Δε y If the wavefront is E′(x,y,z,t), then the light intensity becomes I. out (x out ,y out After the light rays are deflected, an image is formed at point G on the image plane; After distortion occurs in a high frame rate image, the intensities of points W and G both change; The wavefront variation E′(x,y,z,t)-E(x,y,z,t) and the transmission parameter variation (θ) are calculated. in_x +Δε x θ in_y +Δε y This allows us to obtain the change in light intensity I at a specific point on a high frame rate image. out (x out ,y out )-I in (x in ,y in Finally, the corrected high frame rate image is obtained.

Images