Infrared target simulation method and system based on diffraction theory

Abstract

The present invention provides an infrared target simulation method and system based on diffraction theory, and specifically relates to the field of laser transmission technology. The infrared target simulation method includes: obtaining an incident light field of a simulated transmission laser and a preset refractive index spatial distribution matrix, wherein the preset refractive index spatial distribution matrix is ​​obtained based on the refractive index parameters of a simulated optical system; based on the preset refractive index spatial distribution matrix, dividing the simulated optical system into a plurality of subspaces along the transmission direction of the incident light field, wherein the refractive index variation characteristics and transmission distances in each subspace are different; determining a transmission strategy for the refractive index variation characteristics of each subspace and the transmission distance of each subspace; based on the respective transmission strategies of each subspace, simulating the transmission of the incident light field in a plurality of subspaces in turn to obtain an outgoing light field.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to the field of laser transmission technology, and more specifically to an infrared target simulation method and system based on diffraction theory. Background Art

[0002] The spatial transmission method of laser light field is mainly used to study the transmission law of laser in complex environment space and optical system. In engineering application, geometric optical tracing method is mainly used to realize the simulation of transmission effect to assist design. Because infrared laser has the characteristics of good coherence and strong volatility, the interference effect and diffraction effect of infrared laser in the transmission process cannot be ignored. Therefore, it is more meaningful to use wave optics theory to study the interference effect and diffraction effect of infrared laser in the transmission process. The light intensity of infrared laser after long-distance transmission is weak and the diffraction effect is significant. The transmission distance of infrared laser in long-distance transmission is uncertain, and the incident angle when entering the infrared target system is also uncertain. In addition, the interference effect and diffraction effect of infrared laser in the transmission process of infrared target system cannot be ignored. Therefore, how to obtain more accurate, efficient and realistic infrared target simulation effect is a technical problem that needs to be solved urgently. Summary of the invention

[0003] In view of this, the present invention provides an infrared target simulation method and system based on diffraction theory, which can obtain a more accurate and realistic infrared target simulation effect.

[0004] The first aspect of the present invention provides an infrared target simulation method based on diffraction theory, and the infrared target simulation method includes: obtaining an incident light field of a simulated transmission laser and a preset refractive index spatial distribution matrix, wherein the preset refractive index spatial distribution matrix is ​​obtained based on the refractive index parameters of the simulated optical system; based on the preset refractive index spatial distribution matrix, dividing the simulated optical system along the transmission direction of the incident light field into a plurality of subspaces, wherein the refractive index change characteristics and transmission distances in each of the subspaces are different; determining a transmission strategy for the refractive index change characteristics of each subspace and the transmission distance of each subspace; and based on the respective transmission strategies of each subspace, simulating the transmission of the incident light field in the plurality of subspaces in turn to obtain an exit light field.

[0005] According to an embodiment of the present invention, the above-mentioned simulated optical system is divided into a plurality of subspaces along the transmission direction of the above-mentioned incident light field based on the above-mentioned preset refractive index spatial distribution matrix, including: calculating the gradient value of the above-mentioned preset refractive index spatial distribution matrix; according to the above-mentioned gradient value, the above-mentioned simulated optical system is divided into a plurality of subspaces along the transmission direction of the above-mentioned incident light field.

[0006] According to an embodiment of the present invention, the transmission strategy is determined for the refractive index variation characteristics of each of the above-mentioned subspaces and the transmission distance of each of the above-mentioned subspaces, including: for each of the above-mentioned subspaces, according to the above-mentioned preset refractive index spatial distribution matrix, obtaining the refractive index spatial distribution matrix of the above-mentioned subspace; according to the refractive index spatial distribution matrix of the above-mentioned subspaces, calculating the refractive index contrast of the above-mentioned subspace; according to the above-mentioned refractive index contrast and the above-mentioned transmission distance, determining the above-mentioned transmission strategy.

[0007] According to an embodiment of the present invention, the transmission strategy is determined based on the refractive index contrast and the transmission distance, including: when the refractive index contrast is not equal to zero, the transmission strategy is determined to be light beam transmission; when the refractive index contrast is equal to zero and the transmission distance is greater than zero and less than a first threshold, the transmission strategy is determined to be vector diffraction integral transmission; when the refractive index contrast is equal to zero and the transmission distance is greater than the first threshold and less than the second threshold, the transmission strategy is determined to be angular spectrum diffraction transmission; when the refractive index contrast is equal to zero and the transmission distance is greater than the second threshold, the transmission strategy is determined to be Fresnel diffraction transmission.

[0008] According to an embodiment of the present invention, based on the transmission strategy of each of the above-mentioned subspaces, the above-mentioned incident light field is simulated and transmitted in sequence in the above-mentioned multiple subspaces to obtain an exit light field, including: based on the above-mentioned light beam transmission, when the above-mentioned incident light field is simulated and transmitted to the first subspace, the first subspace exit light field of the above-mentioned first subspace is obtained according to the first subspace incident light field of the above-mentioned first subspace; based on the above-mentioned angular spectrum diffraction transmission, when the above-mentioned incident light field is simulated and transmitted to the second subspace, the second subspace exit light field of the above-mentioned second subspace is obtained according to the second subspace incident light field of the above-mentioned second subspace; based on the above-mentioned Fresnel diffraction transmission, when the above-mentioned incident light field is simulated and transmitted to the third subspace, the third subspace exit light field of the above-mentioned third subspace is obtained according to the third subspace incident light field of the above-mentioned third subspace.

[0009] According to an embodiment of the present invention, the first subspace exit light field of the first subspace is obtained based on the first subspace incident light field of the first subspace, including: determining the transmission function of the first subspace according to the refractive index distribution of the first subspace and the wavelength of the simulated transmission laser; dividing the incident light field of the first subspace to obtain incident light fields of multiple sub-regions of the first subspace; multiplying the incident light field of each sub-region by the transmission function to obtain the exit light field of each sub-region; and splicing the exit light fields of the multiple sub-regions to obtain the exit light field of the first subspace.

[0010] According to an embodiment of the present invention, obtaining the second subspace exit light field of the second subspace according to the second subspace incident light field of the second subspace includes: obtaining the second subspace exit light field according to the second subspace incident light field and the transmission distance in the second subspace.

[0011] According to an embodiment of the present invention, obtaining the third subspace exit light field of the third subspace according to the third subspace incident light field of the third subspace includes: performing an integration operation on the third subspace incident light field to obtain the third subspace exit light field.

[0012] According to an embodiment of the present invention, the refractive index contrast of the subspace is calculated based on the refractive index spatial distribution matrix of the subspace, including: calculating the refractive index contrast of the subspace based on the maximum value of the refractive index element and the minimum value of the refractive index element of the refractive index spatial distribution matrix of the subspace.

[0013] Another aspect of the present invention provides an infrared target simulation system based on diffraction theory, including: an acquisition module, used to acquire an incident light field and a preset refractive index spatial distribution matrix, wherein the preset refractive index spatial distribution matrix is ​​obtained based on the refractive index parameters of the simulated optical system; a division module, used to divide the simulated optical system along the transmission direction of the incident light field into multiple subspaces based on the preset refractive index spatial distribution matrix, wherein the refractive index change characteristics and transmission distances in each subspace are different; a determination module, used to determine a transmission strategy for the refractive index change characteristics of each subspace and the transmission distance of each subspace; and an obtaining module, used to simulate the transmission of the incident light field in the multiple subspaces in turn based on the respective transmission strategies of each subspace to obtain an exit light field.

[0014] According to an embodiment of the present invention, the simulated optical system is divided into a plurality of subspaces along the transmission direction of the incident light field according to the refractive index parameters of the simulated optical system, and the transmission strategy of each subspace is determined based on the refractive index change characteristics of each subspace and the transmission distance of each subspace. Based on the respective transmission strategies of each subspace, the laser transmission in the region of the spatial distribution of the known refractive index can be realized, the light field distribution of the outgoing light field can be quickly inferred based on the incident light field, the light field distribution of the incident light field is not limited, and the infrared target with a wide incident angle or a far field can be simulated, and a more accurate, efficient and realistic infrared target simulation effect can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0016] Figure 1The flowchart of the infrared target simulation method based on diffraction theory according to an embodiment of the present invention is schematically shown.

[0017] Figure 2 A schematic diagram of an incident light field and an outgoing light field of an infrared target simulation method based on diffraction theory according to an embodiment of the present invention is schematically shown.

[0018] Figure 3 A schematic diagram of a spatial light modulation device of an infrared target simulation method based on diffraction theory according to an embodiment of the present invention is schematically shown.

[0019] Figure 4 A schematic diagram of an infrared target simulation system based on diffraction theory according to an embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0021] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0022] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0023] When using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc. When using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, or C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.

[0024] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present invention. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present invention.

[0025] When a laser beam passes through a turbulent atmosphere, it will be affected by the atmospheric turbulence and will show divergence, distortion, flicker, etc. After long-distance transmission, the laser beam will become divergent, energy will be lost, and the beam quality will decrease.

[0026] When the infrared laser is incident on the infrared target system after long-distance transmission, the scalar diffraction theory is usually used to achieve high-precision and high-speed light field calculations when it comes to non-wavelength-level wave optics numerical calculations. Scalar diffraction theory is a laser transmission calculation method based on basic mathematical and physical laws such as Maxwell's equations and fast Fourier transform. Scalar diffraction theory is usually used in laser spatial transmission research, laser modulation of optical systems, and atmospheric turbulence effects in complex environments. Scalar diffraction theory can realize laser transmission within the range of known refractive index spatial distribution and absorptivity spatial distribution, and quickly infer the light field distribution of the outgoing light field through the incident light field.

[0027] Figure 1 The flowchart of the infrared target simulation method based on diffraction theory according to an embodiment of the present invention is schematically shown.

[0028] like Figure 1 As shown, the infrared target simulation method based on diffraction theory includes operations S110 to S140.

[0029] In operation S110, an incident light field of a simulated transmission laser and a preset refractive index spatial distribution matrix are acquired, where the preset refractive index spatial distribution matrix is ​​obtained based on a refractive index parameter of a simulated optical system.

[0030] According to an embodiment of the present invention, the infrared laser after long-distance transmission is simulated by simulating the transmission laser, and the infrared target system receiving the infrared laser is simulated by simulating the optical system. The light intensity of the infrared laser after long-distance transmission is weak, the transmission distance of the infrared laser for long-distance transmission is uncertain, and the incident angle when incident on the infrared target system is also uncertain. The far-field distance that can be simulated and calculated is such as a hundred-meter distance, the near-field distance is such as a centimeter distance, and the wider incident angle is such as negative ten degrees to positive ten degrees.

[0031] According to an embodiment of the present invention, the simulated light field can be directly obtained through a detector and introduced into a processor to obtain an incident light field. The simulated light field can also be directly obtained through an algorithm as the incident light field.

[0032] According to an embodiment of the present invention, the intensity matrix of the simulated light field can be used It means that the phase matrix of the simulated light field can be expressed as The incident light field can be expressed as It means that the incident light field Any element of It can be expressed as:

[0033] (1);

[0034] in, is an imaginary unit, , , The number of rows of the matrix representing the incident light field, The number of columns of the matrix representing the incident light field.

[0035] According to an embodiment of the present invention, based on the composition of the simulated optical system with known refractive index distribution, the preset refractive index spatial distribution matrix can be obtained through optical system analysis and division algorithm. ,in, is the refractive index spatial distribution matrix In the incident light field The simulated optical system can include components such as lenses, apertures, prisms, windows, and gratings.

[0036] In operation S120, based on a preset refractive index spatial distribution matrix, the simulated optical system is divided into a plurality of subspaces along the transmission direction of the incident light field, wherein the refractive index variation characteristics and transmission distances in each subspace are different.

[0037] In operation S130, a transmission strategy is determined according to the refractive index variation characteristics of each subspace and the transmission distance of each subspace.

[0038] In operation S140, based on the transmission strategy of each subspace, the incident light field is simulated and transmitted in the plurality of subspaces in sequence to obtain an outgoing light field.

[0039] According to the embodiments of the present invention, infrared lasers with far field or near field and wider incident angles can be simulated by simulating transmission lasers; the simulated optical system is divided into multiple subspaces along the transmission direction of the incident light field according to the refractive index parameters of the simulated optical system, and the transmission strategy of each subspace is determined based on the refractive index change characteristics of each subspace and the transmission distance of each subspace. Based on the respective transmission strategies of each subspace, the laser transmission in the area with known spatial distribution of refractive index can be realized, and the light field distribution of the outgoing light field can be quickly inferred based on the incident light field, so that a more accurate, efficient and realistic infrared target simulation effect can be obtained.

[0040] In one example, the incident light field is obtained through a detector, and the matrix size of the incident light field is the resolution of the detector. An irradiation laser can be generated by a laser. The irradiation laser after power reduction through an infrared attenuation plate can simulate an infrared laser after long-distance transmission, and can be detected by a planar array infrared detector to obtain a simulated light field. The simulated light field is converted into a floating-point matrix and normalized to obtain an intensity matrix of the simulated light field; a zero matrix of the same dimension is constructed as a phase matrix of the simulated light field; the intensity matrix of the simulated light field and the phase matrix of the simulated light field are multiplied to obtain the incident light field. The planar array infrared detector can be a short-wave infrared detector, the main component material of the short-wave infrared detector is silicon or indium gallium arsenide, and the response band is 1μm-2μm. The planar array infrared detector can be a medium-wave infrared detector, the main component material of the medium-wave infrared detector is indium antimonide or mercury cadmium telluride, and the response band is 2.5μm-5μm. The array infrared detector can also be a long-wave infrared detector. The main component material of the long-wave infrared detector is vanadium dioxide or mercury cadmium telluride, and the response band is 8μm-14μm. The detector's use band can be selected according to the actual scenario.

[0041] In one example, the incident light field is obtained by constructing a grayscale image, and the matrix size of the incident light field is the resolution of the grayscale image. The light field of the grayscale image with known spatial distribution is matrixed, and each element is represented by a real number to represent the relative value of the light field intensity and normalized to obtain a simulated light field; the simulated light field is converted into a floating-point matrix and the grayscale value range is converted into the [0,1] interval, which is enlarged 255 times and rounded as a display matrix to obtain an intensity matrix of the simulated light field; a zero matrix of the same dimension and size is constructed as a phase matrix of the simulated data; the intensity matrix of the simulated light field and the phase matrix of the simulated light field are multiplied to obtain the incident light field.

[0042] In one example, a matrix is ​​constructed by a beam function to obtain an incident light field, and the matrix size of the incident light field is the resolution of the constructed matrix. The beam function is converted into a floating-point matrix and normalized to obtain an intensity matrix of the simulated light field; the required phase function is selected to derive the phase matrix; the intensity matrix of the simulated light field and the phase matrix of the simulated light field are multiplied to obtain the incident light field. The beam function can construct an intensity matrix and a phase matrix of the simulated light field based on the mathematical representation of the ideal light field. The beam function can be a fundamental mode Gaussian beam function, a higher-order mode Gaussian beam function, a flat-top beam function, or a Bessel beam function.

[0043] Figure 2 A schematic diagram of an incident light field and an outgoing light field of an infrared target simulation method based on diffraction theory according to an embodiment of the present invention is schematically shown.

[0044] like Figure 2 As stated, Figure 2(a) in the figure is a schematic diagram showing the incident light field acquired by the detector. Figure 2 The incident light field in (a) is simulated and transmitted by the infrared target simulation method based on diffraction theory, and the output light field is as follows: Figure 2 As shown in (b) in .

[0045] According to an embodiment of the present invention, based on a preset refractive index spatial distribution matrix, the simulated optical system is divided into a plurality of subspaces along the transmission direction of the incident light field, including: calculating the gradient value of the preset refractive index spatial distribution matrix ; According to the gradient value , the simulated optical system is divided into Subspace ,in, , Is a positive integer.

[0046] According to an embodiment of the present invention, the gradient value can represent the speed of the change of the refractive index, and the subspace is divided according to the speed of the change of the refractive index.

[0047] According to an embodiment of the present invention, for each subspace , according to the preset refractive index spatial distribution matrix , and obtain the refractive index spatial distribution matrix of the subspace ; According to the refractive index spatial distribution matrix of the subspace , calculate the refractive index contrast of the subspace ; Based on the refractive index contrast and transmission distance , determine the transmission strategy.

[0048] According to an embodiment of the present invention, the refractive index contrast can also characterize the degree of refractive index change of the subspace. The transmission distance represents the distance of simulated transmission of the incident light field in the subspace. Evaluation and division are performed based on the degree of refractive index change and the transmission distance, and a transmission strategy for each space is formulated.

[0049] According to an embodiment of the present invention, for each subspace , in the refractive index contrast When the refractive index contrast is not equal to zero, the transmission strategy is determined to be beam transmission; When the transmission distance is greater than zero and less than the first threshold, the transmission strategy is determined to be vector diffraction integral transmission; when the refractive index contrast When the transmission distance is greater than the first threshold value and less than the second threshold value, the transmission strategy is determined to be angular spectrum diffraction transmission; when the refractive index contrast is When φ is equal to zero and the transmission distance is greater than the second threshold, it is determined that the transmission strategy is Fresnel diffraction transmission.

[0050] According to the present invention, the first threshold can be expressed as , the second threshold can be expressed as ,in, is the wavelength of the transmitted laser, is the step size of the grid division of the simulated optical system. The first threshold represents the boundary value between micro and macro, which is in the order of hundreds of wavelengths. When the transmission distance is less than the first threshold, the influence of the vector diffraction integral phase change cannot be ignored, and the scalar diffraction method cannot be used for calculation. The second threshold represents the boundary value between the near field and the far field. When the transmission distance is greater than the first threshold and less than the second threshold, the transmission calculation accuracy of the angular spectrum diffraction transmission is high, and the influence of spectrum leakage is minimal.

[0051] According to an embodiment of the present invention, the basic diffraction theory applicable to each subspace is determined according to the refractive index contrast and the transmission distance, and the incident light field is modulated and coupled based on the basic diffraction theory to obtain the outgoing light field.

[0052] According to the embodiment of the present invention, for the vector diffraction integral transmission whose transmission distance is greater than zero and less than the first threshold value, the transmission distance is extremely small, and this situation rarely occurs.

[0053] According to an embodiment of the present invention, based on light beam transmission, when the incident light field Simulate transmission to the first subspace , according to the first subspace The first subspace incident light field , and get the first subspace The first subspace output light field .

[0054] According to an embodiment of the present invention, the beam transmission may be performed by performing transmission calculations using a spatially divided beam propagation method.

[0055] According to an embodiment of the present invention, according to the first subspace Refractive index distribution and the wavelength of the simulated transmission laser , determine the first subspace The transfer function .

[0056] According to the first subspace Refractive index distribution , we can get the first subspace Refractive index distribution function .

[0057] Defining the transfer function for:

[0058] (2);

[0059] in, , represents the square of the transverse wave number, Represents the first subspace The effective refractive index, To indicate a plural unit, Indicates the step size calculated along the transmission direction.

[0060] According to an embodiment of the present invention, the first subspace incident light field is divided into the first subspace The incident light field of multiple sub-areas .

[0061] According to an embodiment of the present invention, the incident light field of each sub-region With the transfer function Multiply them together to get the outgoing light field of each sub-area .

[0062] (3);

[0063] Defining Correction Factors for:

[0064] (4);

[0065] in, , Represents the first subspace The refractive index distribution function, Represents the incident light field of the sub-region The distribution function of represents the Fourier operation, represents the inverse Fourier operation, Represents the outgoing light field of each sub-region The distribution function of .

[0066] According to an embodiment of the present invention, the outgoing light fields of the plurality of sub-areas are Splice to get the outgoing light field of the first subspace .

[0067] According to an embodiment of the present invention, the second subspace outgoing light field under the condition of slowly varying envelope approximation is obtained by performing non-uniform spatial division and fast Fourier transform on the second subspace incident light field to solve the scalar Helmholtz equation.

[0068] According to an embodiment of the present invention, based on angular spectrum diffraction transmission, when the incident light field Simulate transmission to the second subspace , according to the second subspace The second subspace incident light field , and obtain the second subspace The second subspace outgoing light field .

[0069] According to an embodiment of the present invention, the angular spectrum diffraction transmission may be performed by performing transmission calculation using an angular spectrum diffraction algorithm.

[0070] According to an embodiment of the present invention, according to the second subspace incident light field and the transmission distance in the second subspace , and get the outgoing light field of the second subspace .

[0071] According to an embodiment of the present invention, according to the second subspace Transmission media and transmission distance , determine the transfer factor.

[0072] For example, the second subspace The transmission medium can be free space or dielectric space. The transmission factor is related to the refractive index. Related, choose frequency domain transmission method, transmission factor It can be expressed as:

[0073] (5);

[0074] in, is a plural unit, Represents the incident light field in the second subspace The distribution function of Represents the incident light field in the second subspace The spatial frequency domain expression after Fourier transform is: Represents the wave number (scalar).

[0075] The second subspace outgoing light field It can be expressed as:

[0076] (6);

[0077] in, Represents the incident light field in the second subspace Perform a two-dimensional fast Fourier transform to decompose the incident light field of the second subspace into a series of simple harmonic plane waves transmitted in different directions. When the incident light field of the second subspace is transmitted in free space, the wavefront shape does not change, and only a phase shift related to the transmission distance is generated, which acts on the spatial frequency of the incident light field of the second subspace to obtain the spatial frequency of the outgoing light field of the second subspace. The outgoing light field of the second subspace is obtained by a two-dimensional fast Fourier transform. .

[0078] According to an embodiment of the present invention, fast calculation of light field transmission in the second subspace is achieved by performing fast Fourier transform on the incident light field in the second subspace.

[0079] For example, the second subspace The transmission medium can be a thin lens, and the transmission factor is related to the focal length and refractive index Related, select the spatial transmission method, the transmission factor It can be expressed as:

[0080] (7);

[0081] in, is a plural unit, Represents the incident light field in the second subspace The distribution function of Represents the wave number (scalar).

[0082] The second subspace outgoing light field It can be expressed as:

[0083] (8).

[0084] According to an embodiment of the present invention, based on the Fresnel diffraction transmission, when the incident light field Simulation transmission to the third subspace , according to the third subspace The incident light field in the third subspace , and obtain the third subspace The third subspace outgoing light field .

[0085] According to an embodiment of the present invention, the Fresnel diffraction transmission may be performed by performing transmission calculation using a wide-angle Fresnel diffraction method.

[0086] According to an embodiment of the present invention, the incident light field of the third subspace Perform an integral operation to obtain the output light field of the third subspace .

[0087] For example, the off-axis diffraction light field can be quickly solved by introducing high-order Taylor approximation and fast Fourier transform. The fast Fourier transform obtains the third subspace outgoing light field in the form of integral transform. , which can be expressed as:

[0088] (9);

[0089] in, , is a plural unit;

[0090] in, ;

[0091] in, , , .

[0092] According to the embodiment of the present invention, the effective range of the scalar diffraction integral can be effectively broadened by the integral transformation on the basis of satisfying the fast Fourier transform form, and the accurate calculation of the light field transmission in the off-axis region can be achieved.

[0093] According to an embodiment of the present invention, according to the refractive index spatial distribution matrix of the subspace The maximum value of the refractive index element and the minimum value of the refractive index element , calculate the subspace Refractive index contrast . Refractive index contrast It can be expressed as:

[0094] (10);

[0095] in, , .

[0096] According to an embodiment of the present invention, based on the composition of the simulated optical system, the preset absorption rate spatial distribution matrix can be obtained through the optical system analysis and division algorithm. ; According to the preset absorption rate spatial distribution matrix , the attenuation of the light intensity of the simulated transmission laser after transmission in each subspace can be calculated; ignoring the emission of the optical device interface, the The light intensity after transmission in the subspace is The light intensity of the subspace times.

[0097] According to the embodiments of the present invention, the infrared target simulation method based on the diffraction theory of the embodiments of the present invention can effectively simulate the transmission effect of the infrared target on the infrared laser received after long-distance transmission. Through different transmission strategies, based on the angular spectrum diffraction algorithm, the space-divided beam transmission method and the optical transmission calculation method coupled with the wide-angle Fresnel diffraction method, it is possible to perform accurate and stable simulation transmission calculations of infrared laser light fields in multiple subspaces, and realize accurate analysis and simulation of infrared optoelectronic target characteristics in a laboratory environment.

[0098] The infrared target simulation method based on the diffraction theory of the embodiment of the present invention can obtain the light field distribution of the outgoing light field of the infrared laser after long-distance transmission and after passing through the infrared target. Based on the light field distribution information of the outgoing light field, the output light field of the real infrared laser is obtained through the spatial light modulation device. The application of the infrared target simulation method based on the diffraction theory of the embodiment of the present invention is described below through a specific embodiment.

[0099] Figure 3 A schematic diagram of a spatial light modulation device of an infrared target simulation method based on diffraction theory according to an embodiment of the present invention is schematically shown.

[0100] like Figure 3 As shown, the spatial light modulation device includes an infrared detector 1, a host computer 2, a controller 3, an infrared laser 4, a telescope group rotating wheel 5, a variable aperture 6, a phase-type spatial light modulator 7 and an amplitude-type spatial light modulator 8.

[0101] Generate a simulated light field through an infrared detector 1; import the simulated light field into a host computer 2 to obtain an incident light field; use the infrared target simulation method based on diffraction theory of an embodiment of the present invention to simulate the transmission of the incident light field to obtain an outgoing light field; output a phase modulation signal based on the phase information of the outgoing light field; output an amplitude modulation signal based on the amplitude information of the outgoing light field.

[0102] The controller 3 is connected to the host computer 2 to receive the outgoing light field information; by analyzing the outgoing light field information, the infrared laser 4, the telescope group wheel 5, the variable iris 6, the phase-type spatial light modulator 7 and the amplitude-type spatial light modulator 8 are controlled. The infrared laser 4 outputs the infrared laser; the telescope group wheel 5 and the variable iris 6 pre-modulate the light field of the infrared laser; in response to the phase modulation signal, the phase-type spatial light modulator 7 is controlled by the controller 3 to adjust the phase information of the light field distribution of the infrared laser; in response to the amplitude modulation signal, the amplitude-type spatial light modulator 8 is controlled by the controller 3 to adjust the amplitude information of the light field distribution of the infrared laser, and the output light field is obtained.

[0103] In one example, the infrared laser 4 includes a short-wave infrared laser module, a medium-wave infrared laser module, a long-wave infrared laser module, and a fiber collimator. The infrared laser 4 can be a replaceable light source, and the short-wave infrared laser module, the medium-wave infrared laser module, and the long-wave infrared laser module can output infrared lasers through pigtails. The fiber collimator serves as a spatial coupling module of the pigtail to output a parallel light beam of a target band. The short-wave infrared laser module can output infrared lasers with wavelengths of 1064 nm and 1550 nm; the medium-wave infrared laser module can output infrared lasers with a wavelength band of 3μm-5μm; and the long-wave infrared laser module can output infrared lasers with a wavelength band of 8μm-12μm.

[0104] In one example, the telescope assembly wheel 5 can adjust the infrared laser by selecting a suitable magnification as required, for example, the magnification can be 2×, 4×, 8×, 16×. The variable aperture 6 can be infinitely adjusted, and can output a flat-top beam by limiting the infrared laser as required.

[0105] In one example, the phase-type spatial light modulator 7 can achieve two-dimensional modulation of the spatial light phase through the liquid crystal structure between the CMOS chip and the transparent electrode on the glass substrate. The amplitude-type spatial light modulator 8 can achieve two-dimensional modulation of the spatial light intensity through a glass substrate with an anti-reflection coating and a CMOS chip with a galvanometer.

[0106] In one example, the controller 3 can be a programmable gate array, which can adjust the external laser 4, the telescope group wheel 5 and the variable aperture 6 in sequence according to the light field information of the outgoing light field through the same scheduling control of the programmable gate array. The light field of the infrared laser with the wavelength, the area and the power density meeting the standard is obtained. After modulation by the phase-type spatial light modulator 7 and the amplitude-type spatial light modulator 8, the output light field is obtained.

[0107] Figure 4 A schematic diagram of an infrared target simulation system based on diffraction theory according to an embodiment of the present invention is schematically shown.

[0108] like Figure 4 As shown, the infrared target simulation system based on diffraction theory includes an acquisition module 410 , a division module 420 , a determination module 430 and a obtaining module 440 .

[0109] The acquisition module 410 is used to acquire the incident light field of the simulated transmission laser and the preset refractive index spatial distribution matrix, where the preset refractive index spatial distribution matrix is ​​obtained based on the refractive index parameters of the simulated optical system.

[0110] The division module 420 is used to divide the simulated optical system into a plurality of subspaces along the transmission direction of the incident light field based on a preset refractive index spatial distribution matrix, wherein the refractive index variation characteristics and transmission distances in each subspace are different.

[0111] The determination module 430 is used to determine a transmission strategy according to the refractive index variation characteristics of each subspace and the transmission distance of each subspace.

[0112] The obtaining module 440 is used to simulate the transmission of the incident light field in multiple subspaces in sequence based on the transmission strategy of each subspace to obtain the output light field.

[0113] According to an embodiment of the present invention, the partitioning module 420 includes a first calculation submodule and a partitioning submodule.

[0114] The first calculation submodule is used to calculate the gradient value of the preset refractive index spatial distribution matrix.

[0115] The division submodule is used to divide the simulated optical system into a plurality of subspaces along the transmission direction of the incident light field according to the gradient value.

[0116] According to an embodiment of the present invention, the determination module 430 includes a first obtaining submodule, a second calculating submodule and a determining submodule.

[0117] The first obtaining submodule is used to obtain the refractive index spatial distribution matrix of each subspace according to a preset refractive index spatial distribution matrix.

[0118] The second calculation submodule is used to calculate the refractive index contrast of the subspace according to the refractive index spatial distribution matrix of the subspace.

[0119] The determination submodule is used to determine the transmission strategy according to the refractive index contrast and the transmission distance.

[0120] According to an embodiment of the present invention, the determining submodule includes a first determining unit, a second determining unit, a third determining unit and a fourth determining unit.

[0121] The first determining unit is used to determine that the transmission strategy is light beam transmission when the refractive index contrast is not equal to zero.

[0122] The second determining unit is used to determine that the transmission strategy is vector diffraction integral transmission when the refractive index contrast is zero and the transmission distance is greater than zero and less than a first threshold.

[0123] The third determining unit is used to determine that the transmission strategy is angular spectrum diffraction transmission when the refractive index contrast is zero and the transmission distance is greater than the first threshold and less than the second threshold.

[0124] The fourth determining unit is configured to determine that the transmission strategy is Fresnel diffraction transmission when the refractive index contrast is zero and the transmission distance is greater than a second threshold.

[0125] According to an embodiment of the present invention, the obtaining module 440 includes a second obtaining submodule, a third obtaining submodule and a fourth obtaining submodule.

[0126] The second obtaining submodule is used for obtaining the first subspace outgoing light field of the first subspace according to the first subspace incident light field of the first subspace based on the light beam transmission when the incident light field is simulated and transmitted to the first subspace.

[0127] The third obtaining submodule is used for transmission based on angular spectrum diffraction. When the incident light field is simulated and transmitted to the second subspace, the second subspace exit light field of the second subspace is obtained according to the second subspace incident light field of the second subspace.

[0128] The fourth sub-module is obtained. Based on Fresnel diffraction transmission, when the incident light field is simulated and transmitted to the third subspace, the third subspace outgoing light field of the third subspace is obtained according to the third subspace incident light field of the third subspace.

[0129] According to an embodiment of the present invention, the second obtaining submodule includes a fifth determining unit, a first obtaining unit, a second obtaining unit and a third obtaining unit.

[0130] The fifth determining unit is used to determine the transmission function of the first subspace according to the refractive index distribution of the first subspace and the wavelength of the simulated transmission laser.

[0131] The first obtaining unit is used to divide the incident light field of the first subspace to obtain the incident light fields of multiple sub-areas of the first subspace.

[0132] The second obtaining unit is used to multiply the incident light field of each sub-region by the transmission function to obtain the outgoing light field of each sub-region.

[0133] The third obtaining unit is used to splice the respective emergent light fields of the plurality of sub-areas to obtain the emergent light field of the first subspace.

[0134] According to an embodiment of the present invention, the third obtaining submodule includes a fourth obtaining unit.

[0135] The fourth obtaining unit is used to obtain the second subspace outgoing light field according to the second subspace incident light field and the transmission distance in the second subspace.

[0136] According to an embodiment of the present invention, the fourth obtaining submodule includes a fifth obtaining unit.

[0137] The fifth obtaining unit is used to perform an integration operation on the incident light field of the third subspace to obtain the outgoing light field of the third subspace.

[0138] According to an embodiment of the present invention, the second computing submodule includes a computing unit.

[0139] The calculation unit is used to calculate the refractive index contrast of the subspace according to the maximum value and the minimum value of the refractive index element of the refractive index spatial distribution matrix of the subspace.

[0140] The embodiments of the present invention have been described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment has been described above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. The scope of the present invention is limited by the attached embodiments and their equivalents. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A method for simulating infrared targets based on diffraction theory, characterized in that: The infrared target simulation method comprises: Acquire an incident light field of a simulated transmission laser and a preset refractive index spatial distribution matrix, wherein the preset refractive index spatial distribution matrix is ​​obtained based on a refractive index parameter of a simulated optical system; Based on the preset refractive index spatial distribution matrix, the simulated optical system is divided into a plurality of subspaces along the transmission direction of the incident light field, wherein the refractive index variation characteristics and transmission distances in each of the subspaces are different; Determining a transmission strategy according to the refractive index variation characteristics of each of the subspaces and the transmission distance of each of the subspaces; Based on the transmission strategy of each subspace, the incident light field is sequentially simulated and transmitted in the multiple subspaces to obtain an outgoing light field; The step of determining a transmission strategy based on the refractive index variation characteristics of each subspace and the transmission distance of each subspace includes: For each of the subspaces, obtaining a refractive index spatial distribution matrix of the subspace according to the preset refractive index spatial distribution matrix; Calculating the refractive index contrast of the subspace according to the refractive index spatial distribution matrix of the subspace; When the refractive index contrast is not equal to zero, determining that the transmission strategy is light beam transmission; When the refractive index contrast is zero and the transmission distance is greater than zero and less than a first threshold, determining that the transmission strategy is vector diffraction integral transmission; When the refractive index contrast is zero and the transmission distance is greater than the first threshold and less than a second threshold, determining that the transmission strategy is angular spectrum diffraction transmission; When the refractive index contrast is equal to zero and the transmission distance is greater than the second threshold, it is determined that the transmission strategy is Fresnel diffraction transmission.

2. The infrared target simulation method based on diffraction theory according to claim 1 is characterized in that: The step of dividing the simulated optical system into a plurality of subspaces along the transmission direction of the incident light field based on the preset refractive index spatial distribution matrix comprises: Calculating the gradient value of the preset refractive index spatial distribution matrix; According to the gradient value, the simulated optical system is divided into a plurality of subspaces along a transmission direction of the incident light field.

3. The infrared target simulation method based on diffraction theory according to claim 1 is characterized in that: The step of simulating and transmitting the incident light field in the plurality of subspaces in sequence based on the transmission strategy of each subspace to obtain an outgoing light field includes: Based on the light beam transmission, when the incident light field is simulated and transmitted to the first subspace, a first subspace exit light field of the first subspace is obtained according to the first subspace incident light field of the first subspace; Based on the angular spectrum diffraction transmission, when the incident light field is simulated and transmitted to the second subspace, a second subspace exit light field of the second subspace is obtained according to the second subspace incident light field of the second subspace; Based on the Fresnel diffraction transmission, when the incident light field is simulated and transmitted to the third subspace, the third subspace exit light field of the third subspace is obtained according to the third subspace incident light field of the third subspace.

4. The infrared target simulation method based on diffraction theory according to claim 3 is characterized in that: The step of obtaining the first subspace outgoing light field of the first subspace according to the first subspace incident light field of the first subspace includes: Determining a transmission function of the first subspace according to the refractive index distribution of the first subspace and the wavelength of the simulated transmission laser; Dividing the incident light field of the first subspace to obtain incident light fields of a plurality of sub-regions of the first subspace; Multiplying the incident light field of each sub-region by the transfer function to obtain the outgoing light field of each sub-region; The emergent light fields of the multiple sub-areas are spliced ​​to obtain the emergent light field of the first subspace.

5. The infrared target simulation method based on diffraction theory according to claim 3 is characterized in that: The step of obtaining the second subspace exit light field of the second subspace according to the second subspace incident light field of the second subspace includes: The second subspace outgoing light field is obtained according to the second subspace incident light field and the transmission distance in the second subspace.

6. The infrared target simulation method based on diffraction theory according to claim 3 is characterized in that: The step of obtaining a third subspace exit light field of the third subspace according to the third subspace incident light field of the third subspace comprises: An integration operation is performed on the incident light field of the third subspace to obtain the outgoing light field of the third subspace.

7. The infrared target simulation method based on diffraction theory according to claim 1 is characterized in that: Calculating the refractive index contrast of the subspace according to the refractive index spatial distribution matrix of the subspace includes: The refractive index contrast of the subspace is calculated according to the maximum value of the refractive index element and the minimum value of the refractive index element of the refractive index spatial distribution matrix of the subspace.

8. An infrared target simulation system based on diffraction theory, characterized in that: include: An acquisition module, used to acquire an incident light field of a simulated transmission laser and a preset refractive index spatial distribution matrix, wherein the preset refractive index spatial distribution matrix is ​​obtained based on a refractive index parameter of a simulated optical system; A division module, configured to divide the simulated optical system into a plurality of subspaces along the transmission direction of the incident light field based on the preset refractive index spatial distribution matrix, wherein the refractive index variation characteristics and transmission distances in each subspace are different; A determination module, used to determine a transmission strategy according to the refractive index variation characteristics of each of the subspaces and the transmission distance of each of the subspaces; The determination module includes: A first obtaining submodule is used to obtain a refractive index spatial distribution matrix of each subspace according to a preset refractive index spatial distribution matrix; A second calculation submodule, configured to calculate the refractive index contrast of the subspace according to the refractive index spatial distribution matrix of the subspace; and A determination submodule, used to determine a transmission strategy according to the refractive index contrast and the transmission distance; Among them, the submodules are determined to include: A first determining unit, configured to determine that the transmission strategy is beam transmission when the refractive index contrast is not equal to zero; A second determining unit is used to determine that the transmission strategy is vector diffraction integral transmission when the refractive index contrast is zero and the transmission distance is greater than zero and less than a first threshold; a third determining unit, configured to determine that the transmission strategy is angular spectrum diffraction transmission when the refractive index contrast is zero and the transmission distance is greater than a first threshold value and less than a second threshold value; and a fourth determining unit, configured to determine that the transmission strategy is Fresnel diffraction transmission when the refractive index contrast is zero and the transmission distance is greater than a second threshold; and The obtaining module is used to simulate the transmission of the incident light field in the multiple subspaces in sequence based on the transmission strategy of each subspace to obtain the output light field.

Images