Cosine corrector and optimization design method and device thereof

Abstract

The invention discloses a cosine corrector and an optimization design method and device thereof, the cosine corrector comprises a cosine corrector body and a light blocking ring, the cosine corrector body is arranged in the light blocking ring, and the method comprises the following steps: obtaining a first expression and a second expression, the first expression is about the loss luminous flux of the incident light incident to the upper surface of the cosine corrector body, and the second expression is about the compensation luminous flux of the incident light incident to the side surface of the cosine corrector body; the error expression describes the relationship between the difference between the compensation luminous flux and the loss luminous flux and the incident angle of the incident light and the structure parameter of the cosine corrector, and the data of the structure parameter of the cosine corrector is determined by using the error expression. And the sum of the difference between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light, which is calculated according to the error expression, meets the requirement. According to the method, the optimal design of the cosine corrector is realized, so that the cosine correction error of the cosine corrector can meet the requirement.

Description

Technical Field

[0001] The invention relates to the field of spectral remote sensing radiation correction, and in particular to a cosine corrector and an optimization design method and device thereof. Background Art

[0002] As a convenient flying platform, drones are increasingly used in the field of low-altitude remote sensing. The drone low-altitude spectral technology, which closely combines drone technology with spectral remote sensing technology, has important application value and is the current research focus in the field of quantitative remote sensing. Data accuracy is the premise and basis for the application of quantitative remote sensing data. Studies have shown that the spatiotemporal variation of atmospheric downwelling radiation is one of the main factors affecting the accuracy of low-altitude spectral remote sensing data. The atmospheric downwelling radiation measurement sensor installed on the back of the drone synchronously detects the change of atmospheric downwelling irradiance, and uses the measurement results for data correction, which can effectively reduce the radiation measurement error introduced by the change of atmospheric downwelling light.

[0003] The atmospheric downlink radiation measurement sensor used in UAV spectral remote sensing mainly includes a cosine corrector, a spectrum selection device and a photodetector. The cosine response characteristics of the cosine corrector are the main factors affecting the accuracy of atmospheric downlink radiation measurement. The cosine corrector is an optical diffusion device installed in front of the photodetector. It captures the light intensity signal within a 180° field of view through the scattering effect of the material. The radiation response of the downlink radiation measurement sensor with an ideal cosine correction function conforms to Lambert's cosine law, that is, the radiation response varies with the cosine of the angle between the incident direction of the light and the normal direction of the detection surface, expressed as:

[0004] ;

[0005] Where Res represents the radiation response, θ represents the angle between the incident direction of the light and the normal direction of the detection surface, and Res0 represents the radiation response when the light is incident perpendicular to the detection surface. The actual cosine corrector has a certain degree of deviation in its correction effect compared to the Lambert cosine curve, which is called the cosine correction error. In order to improve the radiation correction accuracy of spectral remote sensing data, it is necessary to reduce the cosine correction error by optimizing the cosine corrector. At present, there is little research on the optimization of cosine correctors, which results in the fact that the accuracy of atmospheric downlink radiation measurement cannot meet the radiation correction accuracy requirements of quantitative remote sensing. Summary of the invention

[0006] The purpose of the present invention is to provide a cosine corrector and an optimization design method and device thereof, so as to realize the optimization design of the cosine corrector and enable the cosine correction error of the cosine corrector to meet the requirements.

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

[0008] A method for optimizing the design of a cosine corrector, the cosine corrector comprising a cosine corrector body and a light-blocking ring, the cosine corrector body being arranged in the light-blocking ring, so that incident light is incident on the upper surface of the cosine corrector body or the side surface of the cosine corrector body spaced from the inner surface of the light-blocking ring, and then incident on a detector after passing through the cosine corrector body; the method for optimizing the design of a cosine corrector comprises:

[0009] Determining structural parameters of the cosine corrector that affect the cosine correction error;

[0010] Obtaining a first expression, wherein the first expression describes the relationship between the lost light flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the lost light flux is the light flux lost in the process of the incident light being incident on the upper surface of the cosine corrector body, passing through the cosine corrector body and being incident on the detector;

[0011] Obtaining a second expression, wherein the second expression describes the relationship between the compensation luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the compensation luminous flux is the luminous flux of the incident light incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector;

[0012] An error expression is obtained according to the first expression and the second expression, wherein the error expression describes the relationship between the difference between the compensated luminous flux and the lost luminous flux, the incident angle of the incident light, and the structural parameters of the cosine corrector, and the error expression is used to determine the data of the structural parameters of the cosine corrector so that the obtained cosine corrector, according to the error expression, the sum of the differences between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light, calculated to meet the requirements.

[0013] Optionally, the data of the structural parameters of the cosine corrector are determined by using the error expression, so that the obtained cosine corrector, the sum of the differences between the compensation luminous flux and the loss luminous flux within the incident angle range of the incident light calculated according to the error expression, meets the requirements including:

[0014] Using the error expression, an objective function is established, wherein the objective function describes the sum of differences between the compensation luminous flux and the loss luminous flux within the incident angle range of the incident light;

[0015] Solving the objective function to obtain a data set that minimizes the value of the objective function, wherein the data set includes multiple sets of data of the structural parameters;

[0016] According to the data set, data of the structural parameters of the cosine corrector are determined.

[0017] Optionally, the structural parameters include the size of the upper surface of the cosine corrector body, the side size of the cosine corrector body spaced apart from the inner surface of the light-blocking ring, and the spacing distance from the side of the cosine corrector body to the inner surface of the light-blocking ring;

[0018] Solving the objective function and obtaining a data set that minimizes the value of the objective function includes:

[0019] After determining the size of the sensing surface of the detector and the distance from the lower surface of the cosine corrector body to the sensing surface of the detector, solving the objective function to obtain the data set that minimizes the value of the objective function;

[0020] According to the data set, the data for determining the structural parameters of the cosine corrector includes:

[0021] A first relational expression and a second relational expression are obtained according to the data set, wherein the first relational expression describes the relationship between the side dimension of the cosine corrector body spaced apart from the inner surface of the light-blocking ring and the upper surface dimension of the cosine corrector body, and the second relational expression describes the relationship between the spacing distance from the side of the cosine corrector body to the inner surface of the light-blocking ring and the upper surface dimension of the cosine corrector body, so as to determine the upper surface dimension of the cosine corrector body, the side dimension of the cosine corrector body spaced apart from the inner surface of the light-blocking ring, and the spacing distance from the side of the cosine corrector body to the inner surface of the light-blocking ring by using the first relational expression and the second relational expression.

[0022] Optionally, establishing an objective function using the error expression includes:

[0023] A plurality of incident angles are selected within the incident angle range of the incident light, and the error expression is used to obtain the sum of the differences between the compensated luminous flux and the lost luminous flux corresponding to the plurality of incident angles, so as to establish the objective function.

[0024] Optionally, solving the objective function includes:

[0025] Step S1: randomly generate N groups of chromosomes, corresponding to N groups of populations, each group of populations corresponding to a group of data of the structural parameters;

[0026] Step S2: Calculate the population fitness for each group of populations, wherein the population fitness is calculated based on the error expression and the data of the structural parameters corresponding to the population;

[0027] Step S3: Determine whether the value of the population fitness meets the requirement;

[0028] Step S4: Perform population iteration to obtain a new offspring population, and increase the number of iterations by one;

[0029] Step S5: Determine whether the number of iterations reaches the maximum number of iterations. If so, the data of the structural parameters corresponding to the population whose population fitness value meets the requirements is output as the output result; if the number of iterations does not reach the maximum number of iterations, enter step S2.

[0030] Optionally, calculating the population fitness includes:

[0031] For any group of populations, the data of the structural parameters corresponding to this group of populations are substituted into the error expression, and the sum of the differences between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light is calculated according to the obtained error expression. The inverse of the obtained sum of differences is the population fitness of this group of populations.

[0032] Optionally, it also includes:

[0033] For each group of data in the data set, the critical angle corresponding to the group of data is calculated, and the changing trend of the critical angle is obtained according to the critical angle corresponding to each group of data in the data set. The critical angle is the minimum incident angle at which the light blocking ring will block the incident light when the incident light enters the cosine corrector body.

[0034] Optionally, the second expression includes a first sub-expression and a second sub-expression;

[0035] The first sub-expression describes the relationship between the first compensation luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the first compensation luminous flux is the luminous flux of the incident light with an incident angle less than the critical angle incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector;

[0036] The second sub-expression describes the relationship between the second compensation luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the second compensation luminous flux is the luminous flux of the incident light with an incident angle greater than the critical angle incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector;

[0037] The critical angle is the minimum incident angle at which the light-blocking ring blocks the incident light when the incident light enters the cosine corrector body;

[0038] The error expression includes a first error expression and a second error expression. The first error expression describes the relationship between the difference between the first compensating luminous flux and the lost luminous flux, the incident angle of the incident light, and the structural parameters of the cosine corrector. The second error expression describes the relationship between the difference between the second compensating luminous flux and the lost luminous flux, the incident angle of the incident light, and the structural parameters of the cosine corrector.

[0039] A cosine corrector optimization design device, comprising:

[0040] Memory for storing computer programs;

[0041] A processor is used to implement the steps of the cosine corrector optimization design method as described in any one of the above items when executing the computer program.

[0042] A cosine corrector comprises a cosine corrector body and a light-blocking ring, wherein the cosine corrector body is arranged in the light-blocking ring so that incident light is incident on the upper surface of the cosine corrector body or the side surface of the cosine corrector body spaced from the inner surface of the light-blocking ring, and is incident on a detector after passing through the cosine corrector body. The cosine corrector is obtained by using any of the above cosine corrector optimization design methods.

[0043] It can be known from the above technical scheme that the present invention provides a method and device for optimizing the design of a cosine corrector, wherein the cosine corrector includes a cosine corrector body and a light-blocking ring, wherein the cosine corrector body is arranged in the light-blocking ring, and the method includes: obtaining a first expression and a second expression, wherein the first expression is about the loss luminous flux of the incident light incident on the upper surface of the cosine corrector body, and the second expression is about the compensation luminous flux of the incident light incident on the side of the cosine corrector body, and obtaining an error expression, wherein the error expression describes the relationship between the difference between the compensation luminous flux and the loss luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector, and the error expression is used to determine the data of the structural parameters of the cosine corrector, so that the obtained cosine corrector, according to the error expression, the sum of the difference between the compensation luminous flux and the loss luminous flux within the incident angle range of the incident light, calculated and obtained, meets the requirements. The method and device for optimizing the design of a cosine corrector of the present invention realizes the optimized design of the cosine corrector, so that the cosine correction error of the cosine corrector can meet the requirements.

[0044] The cosine corrector provided by the present invention enables the cosine correction error to meet the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] FIG1 is a flow chart of a cosine corrector optimization design method provided by an embodiment of the present invention;

[0047] FIG2 is a schematic diagram of a cosine corrector to which a cosine corrector optimization design method provided by an embodiment of the present invention is applied;

[0048] FIG3 is a schematic diagram showing the principle of obtaining a second expression by integration in a cosine corrector optimization design method provided by an embodiment of the present invention;

[0049] FIG4 is a flow chart of a cosine corrector optimization design method provided by another embodiment of the present invention;

[0050] 5 is a flow chart of solving an objective function of a cosine corrector optimization design method according to an embodiment of the present invention;

[0051] FIG6 is a curve showing a change in the critical angle obtained in the method for optimizing the design of a cosine corrector according to an embodiment of the present invention;

[0052] FIG. 7 is a curve corresponding to the first relational expression and a curve corresponding to the second relational expression obtained in the method for optimizing the design of a cosine corrector according to an embodiment of the present invention.

[0053] The reference numerals in the drawings of the specification include:

[0054] 1-light blocking ring, 2-cosine corrector body, 3-housing, 4-detector. DETAILED DESCRIPTION

[0055] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0056] The present embodiment provides a method for optimizing the design of a cosine corrector, wherein the cosine corrector comprises a cosine corrector body and a light-blocking ring, wherein the cosine corrector body is arranged inside the light-blocking ring, so that incident light is incident on the upper surface of the cosine corrector body or the side surface of the cosine corrector body spaced from the inner surface of the light-blocking ring, and then passes through the cosine corrector body and is incident on a detector.

[0057] Please refer to FIG. 1, which is a flow chart of a cosine corrector optimization design method provided by an embodiment. As shown in the figure, the cosine corrector optimization design method includes the following steps:

[0058] S11: Determine the structural parameters of the cosine corrector that affect the cosine correction error.

[0059] Cosine correction error refers to the deviation between the radiation response of the detector to the incident light after passing through the cosine corrector and the radiation response that satisfies Lambert's cosine law.

[0060] For this cosine corrector, the incident light can be incident on the upper surface of the cosine corrector body, pass through the cosine corrector body and then enter the detector. However, since the light energy will be partially lost when passing through the cosine corrector body, such as the cosine corrector body has absorption loss, refraction loss or reflection loss of the light, it will cause cosine correction error.

[0061] In view of this, for the present cosine corrector, the incident light can be incident on the side of the cosine corrector body that is spaced from the inner surface of the light blocking ring, and then be incident on the detector after passing through the cosine corrector body. This part of the light energy is used to compensate for the light energy lost when the incident light passes through the upper surface of the cosine corrector body, so that the cosine correction error of the present cosine corrector can meet the requirements.

[0062] In this step, the structural parameters of the cosine corrector that affect the cosine correction error are determined based on the structure of the cosine corrector body and the light blocking ring, the light radiation transmission path of the incident light incident on the upper surface of the cosine corrector body, and the light radiation transmission path of the incident light incident on the side of the cosine corrector body that is spaced from the inner surface of the light blocking ring.

[0063] S12: Obtain a first expression, which describes the relationship between the lost luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector. The lost luminous flux is the luminous flux lost in the process of the incident light being incident on the upper surface of the cosine corrector body, passing through the cosine corrector body and being incident on the detector.

[0064] According to the light radiation transmission principle of the incident light incident on the upper surface of the cosine corrector body, passing through the cosine corrector body and incident on the detector, a first expression is established. The first expression can be considered as a mathematical model describing the light radiation transmission process of the incident light incident on the upper surface of the cosine corrector body, passing through the cosine corrector body and incident on the detector.

[0065] S13: Obtain a second expression, which describes the relationship between the compensation luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector. The compensation luminous flux is the luminous flux of the incident light that is incident on the side of the cosine corrector body, passes through the cosine corrector body and is incident on the detector.

[0066] According to the light radiation transmission principle of the incident light incident on the side of the cosine corrector body spaced apart from the inner surface of the light-blocking ring, and incident on the detector after passing through the cosine corrector body, a second expression is established. The second expression can be considered as a mathematical model describing the light radiation transmission process of the incident light incident on the side of the cosine corrector body spaced apart from the inner surface of the light-blocking ring, and incident on the detector after passing through the cosine corrector body.

[0067] In this embodiment, the side surface of the cosine corrector body that is spaced apart from the inner surface of the light-blocking ring may be referred to as an exposed side surface of the cosine corrector body.

[0068] S14: Obtain an error expression according to the first expression and the second expression, wherein the error expression describes the relationship between the difference between the compensated luminous flux and the lost luminous flux, the incident angle of the incident light, and the structural parameters of the cosine corrector, and uses the error expression to determine the data of the structural parameters of the cosine corrector, so that the obtained cosine corrector, the sum of the difference between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light calculated according to the error expression, meets the requirements.

[0069] For the cosine corrector, the difference between the compensated luminous flux and the lost luminous flux can be considered as the cosine correction error of the cosine corrector. The error expression established can be considered as a mathematical model describing the cosine correction error of the cosine corrector. The incident angle range of the incident light refers to the range limited by the minimum incident angle to the maximum incident angle of the incident light.

[0070] The cosine corrector optimization design method of this embodiment establishes a first expression and a second expression. The first expression is about the loss luminous flux of the incident light incident on the upper surface of the cosine corrector body, and the second expression is about the compensation luminous flux of the incident light incident on the side of the cosine corrector body, and an error expression is obtained. The error expression describes the relationship between the difference between the compensation luminous flux and the loss luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector. In this way, a theoretical mathematical model is established for the cosine correction error of the cosine corrector to determine the structural parameter data of the cosine corrector, thereby achieving an optimized design of the cosine corrector so that the cosine correction error of the cosine corrector can meet the requirements.

[0071] In some embodiments, the upper surface of the cosine corrector body is flush with the end face of the light-blocking ring, so that the angular response detected by the detector is closer to the ideal cosine response at all zenith angles. The end face of the light-blocking ring refers to the surface of the light-blocking ring on the incident side of the incident light. For example, reference may be made to FIG2 , which is a schematic diagram of a cosine corrector to which the cosine corrector optimization design method provided in an embodiment is applied. As shown in the figure, the cosine corrector includes a cosine corrector body 2 and a light-blocking ring 1. The cosine corrector body 2 is disposed in the light-blocking ring 1. There is a gap between the side of the cosine corrector body 2 close to the incident side of the incident light and the inner surface of the light-blocking ring 1. This part of the side can be called the exposed side of the cosine corrector body 2.

[0072] In some embodiments, the structural parameters include the size of the upper surface of the cosine corrector body 2, the side size of the cosine corrector body 2 and the inner surface of the light-blocking ring 1, and the distance between the side of the cosine corrector body 2 and the inner surface of the light-blocking ring 1. The structural parameters may also include the size of the sensing surface of the detector 4 and the distance from the lower surface of the cosine corrector body 2 to the sensing surface of the detector 4. For example, in conjunction with reference to FIG. 2, if the cross-section of the cosine corrector body 2 is circular, corresponding to the cosine corrector shown in FIG. 2, the structural parameters may include: the radius R of the upper surface of the cosine corrector body 2, the height h of the side of the cosine corrector body 2 and the inner surface of the light-blocking ring, and the distance b between the side of the cosine corrector body 2 and the inner surface of the light-blocking ring. If the sensing surface of the detector 4 is circular, the structural parameters may also include: the radius r1 of the sensing surface of the detector 4 and the distance d from the lower surface of the cosine corrector body 2 to the sensing surface of the detector 4.

[0073] In some embodiments, the first expression may be expressed as: , where L1 represents the brightness of the incident light incident on the upper surface of the cosine corrector body after passing through the cosine corrector body, and k1 represents the first structural coefficient, which is related to the structural parameters of the cosine corrector. For the cosine corrector shown in FIG2 , the first structural coefficient is related to the size of the upper surface of the cosine corrector body, the size of the sensing surface of the detector, and the distance from the lower surface of the cosine corrector body to the sensing surface of the detector.

[0074] In some implementations, obtaining the first expression may include the following process:

[0075] Calculate the light energy detected after the incident light passes through the upper surface of the cosine corrector body. The luminous flux of the incident sunlight passing through the upper surface of the cosine corrector body due to internal absorption and refraction and reflection loss is expressed as:

[0076] ;

[0077] Wherein, θ represents the incident angle of the incident light, ρ represents the loss rate when the incident light is incident on the upper surface of the cosine corrector body and passes through the cosine corrector body, Represents the luminous flux of incident light.

[0078] According to the optical formula The brightness of the light after internal loss can be expressed as:

[0079] ;

[0080] Where E0 represents the light energy of the incident light, and R represents the radius of the upper surface of the cosine corrector body. 、S=πR 2 The calculation formula for L1 mentioned above is obtained.

[0081] Without considering the measurement error introduced by the transmission loss inside the cosine corrector installation structure, the incident light is incident on the upper surface of the cosine corrector body, and after being transmitted and emitted through the cosine corrector structure, the detector detects the lost luminous flux. ,in:

[0082] .

[0083] Wherein, r1 represents the radius of the sensing surface of the detector, and d represents the distance from the lower surface of the cosine corrector body to the sensing surface of the detector.

[0084] In some embodiments, obtaining the second expression includes: according to the luminous flux differential formula , the incident light is incident on the side of the cosine corrector body, passes through the cosine corrector body and incident on the detector. The second expression is obtained, which is expressed as:

[0085] ; (1)

[0086] Wherein, L represents the brightness, K represents the structural coefficient, i represents the azimuth angle, l represents the irradiation height, R represents the upper surface radius of the cosine corrector body, h represents the side height of the cosine corrector body and the inner surface of the light-blocking ring, r1 represents the sensing surface radius of the detector, and Ω represents the solid angle of the luminous flux.

[0087] For example, reference may be made to Figure 3, which is a schematic diagram of the principle of obtaining the second expression by integration in a cosine corrector optimization design method provided by an embodiment. The light flux of the incident light incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector is analyzed, and the optical path diagram is shown in Figure 3, in which α represents the aperture angle of the sensing surface of the detector corresponding to the side incident light range.

[0088] According to the luminous flux differential formula By performing surface integral on the side light input, the detected side light input is solved and expressed as:

[0089] .

[0090] In some embodiments, the second expression includes a first sub-expression and a second sub-expression;

[0091] The first sub-expression describes the relationship between the first compensation luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the first compensation luminous flux is the luminous flux of the incident light with an incident angle less than the critical angle incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector;

[0092] The second sub-expression describes the relationship between the second compensation luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the second compensation luminous flux is the luminous flux of the incident light with an incident angle greater than the critical angle incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector;

[0093] The critical angle is the minimum incident angle at which the light-blocking ring blocks the incident light when the incident light enters the cosine corrector body.

[0094] Correspondingly, the error expression includes a first error expression and a second error expression, wherein the first error expression describes the relationship between the difference between the first compensating luminous flux and the lost luminous flux and the incident angle of the incident light, and the structural parameters of the cosine corrector, and the second error expression describes the relationship between the difference between the second compensating luminous flux and the lost luminous flux and the incident angle of the incident light, and the structural parameters of the cosine corrector.

[0095] When the incident light with an incident angle less than the critical angle is incident on the cosine corrector body, the light-blocking ring will not block the incident light, and the incident light can directly be incident on the upper surface and exposed side surface of the cosine corrector body (the exposed side surface is the side surface of the cosine corrector body with a gap between the inner surface of the light-blocking ring). When the incident light angle is greater than the critical angle, the incident light can directly be incident on the upper surface of the cosine corrector body, but due to the blocking of the light-blocking ring, the exposed side surface of the cosine corrector body cannot be illuminated by the incident light, and at this time the light-blocking ring will block the incident light.

[0096] Reference may be made to FIG4, which is a flow chart of a cosine corrector optimization design method provided by another embodiment. As shown in the figure, before establishing the first sub-expression and the second sub-expression, the critical angle θ0 may be analyzed and obtained first. The critical angle θ0 is related to the size of the exposed side surface of the cosine corrector body and the spacing distance between the exposed side surface of the cosine corrector body and the inner surface of the light-blocking ring. When the incident angle is less than the critical angle, the exposed side surface of the cosine corrector body is completely placed within the illumination range, and the light-blocking ring does not block the incident light; when the incident angle is greater than the critical angle, the light-blocking ring blocks part of the light to control the amount of light entering. The calculation formula of the critical angle θ0 is as follows:

[0097] .

[0098] In FIG. 4 , the exposed height indicates the size of the exposed side surface of the cosine corrector body, and the groove width indicates the spacing distance from the exposed side surface of the cosine corrector body to the inner surface of the light blocking ring.

[0099] When 0°< θ <θ0, the illumination height l = h, that is, the exposed side of the cosine corrector is all within the incident light illumination range. In this scenario, according to the luminous flux differential formula and formula (1), we can obtain:

[0100] .

[0101] Wherein, k2 represents the second structural coefficient, R represents the upper surface radius of the cosine corrector body, h represents the side height of the interval between the cosine corrector body and the inner surface of the light-blocking ring, and r1 represents the sensing surface radius of the detector.

[0102] And by the optical formula and The illuminance of light incident from the side of the cosine corrector body and exiting the cosine corrector body can be expressed as: Among them, Φ ⊥ It represents the luminous flux incident on the upper surface of the cosine corrector body when the incident light is incident vertically, ρ' represents the loss rate when the incident light is incident on the side of the cosine corrector body and passes through the cosine corrector body, and l represents the irradiation height.

[0103] The radiance can be further obtained, expressed as:

[0104] .

[0105] The first sub-expression can be expressed as: Φ = k2L. The relationship between the deviation of the two and the above parameters is obtained, that is, the first error expression is obtained: .

[0106] When θ0< θ < 90°, the irradiation height , that is, the range of the side of the cosine corrector body that can be illuminated by the incident light is related to the distance b between the side of the cosine corrector body and the inner surface of the light-blocking ring and the incident angle θ. In this scenario, according to the luminous flux differential formula and formula (1), we can get:

[0107] .

[0108] The second sub-expression can be expressed as: Φ=k3L, where k3 represents the third structural coefficient. The second error expression can be solved as: .

[0109] In some embodiments, the data of the structural parameters of the cosine corrector can be determined by using the error expression through the following process, so that the sum of the differences between the compensation luminous flux and the loss luminous flux within the incident angle range of the incident light calculated according to the error expression of the obtained cosine corrector meets the requirements, including the following steps:

[0110] S141: establishing an objective function using the error expression, wherein the objective function describes the sum of differences between the compensation luminous flux and the loss luminous flux within the incident angle range of the incident light;

[0111] S142: solving the objective function to obtain a data set that minimizes the value of the objective function, wherein the data set includes multiple sets of data of the structural parameters;

[0112] S143: Determine the data of the structural parameters of the cosine corrector according to the data set.

[0113] For the present cosine corrector, the sum of the differences between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light can be considered as the global cosine correction error of the cosine corrector.

[0114] For the obtained objective function, the objective function is solved to obtain multiple sets of structural parameter data of the cosine corrector, and the obtained structural parameter data can minimize the value of the objective function. Further, according to the data set, the structural parameter data of the cosine corrector to be designed is determined.

[0115] In this implementation, an error expression is used to establish an objective function that describes the global cosine correction error of the cosine corrector, and multiple groups of structural parameter data of the cosine corrector are obtained by solving the objective function. Then, the structural parameter data of the cosine corrector are determined based on the multiple groups of structural parameter data. In this way, a theoretical mathematical model is established for the cosine correction error of the cosine corrector to determine the structural parameter data of the cosine corrector, so that the optimal structural design can be obtained, and an optimized design scheme for the cosine corrector can be quickly given.

[0116] In some embodiments, establishing the objective function using the error expression includes: selecting multiple incident angles within the incident angle range of the incident light, and using the error expression to obtain the sum of the differences between the compensation luminous flux and the loss luminous flux corresponding to the multiple incident angles to establish the objective function. In some embodiments, multiple incident angles can be selected at equal angle intervals from the minimum incident angle to the maximum incident angle of the incident light. In this embodiment, the angle interval is not limited. In practical applications, it can be selected based on the relationship between the cosine correction error and the incident angle and the error law reflected by the differences corresponding to the multiple incident angles. Exemplarily, the angle interval can be selected as 5°. In theory, multiple incident angles can also be selected from the minimum incident angle to the maximum incident angle according to other angle intervals to calculate the sum of the differences, but because the error size is inversely proportional to the incident angle, the angle interval should not be too large, and it is also necessary to reflect the error law presented by the multiple incident angles, so it is more appropriate to take 5°. In other implementations, the error expression may be integrated within the range from the minimum incident angle to the maximum incident angle of the incident light to establish the objective function, but this implementation has a large amount of calculation.

[0117] The established objective function describes the sum of the difference between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light, or the established objective function is the sum of the absolute values ​​of the difference between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light. For the implementation method of selecting multiple incident angles within the incident angle range of the incident light to establish the objective function using the error expression, the established objective function describes the sum of the difference corresponding to the multiple incident angles, or the established objective function is the sum of the absolute values ​​of the difference corresponding to the multiple incident angles. In some embodiments, the objective function can be established by taking the absolute values ​​of the differences corresponding to each of the multiple incident angles and then summing them. Or the objective function can be established by taking the squares of the differences corresponding to each of the multiple incident angles and then summing them. Exemplarily, the minimum incident angle is 0° and the maximum incident angle is 90°. Multiple incident angles can be selected from 0°-90° to sum the corresponding error values ​​y. Considering the global error, the objective function can be simply expressed as: .

[0118] In some implementations, a genetic algorithm may be used to solve the objective function. Please refer to FIG5 , which is a flow chart of a cosine corrector optimization design method according to an embodiment for solving the objective function. Solving the objective function includes the following process:

[0119] Step S1: randomly generate N groups of chromosomes, corresponding to N groups of populations, each group of populations corresponding to a group of data of the structural parameters;

[0120] Step S2: Calculate the population fitness for each group of populations, wherein the population fitness is calculated based on the error expression and the data of the structural parameters corresponding to the population;

[0121] Step S3: Determine whether the value of the population fitness meets the requirement;

[0122] Step S4: Perform population iteration to obtain a new offspring population, and increase the number of iterations by one;

[0123] Step S5: Determine whether the number of iterations reaches the maximum number of iterations. If so, the data of the structural parameters corresponding to the population whose population fitness value meets the requirements is output as the output result; if the number of iterations does not reach the maximum number of iterations, enter step S2.

[0124] In some embodiments, for each group of chromosomes, the values ​​of the structural parameters corresponding to each group of populations can be obtained by binary coding. Exemplary structural parameters include: the radius R of the upper surface of the cosine corrector body 2, the side height h of the cosine corrector body 2 and the inner surface of the light-blocking ring, and the spacing distance b from the side of the cosine corrector body 2 to the inner surface of the light-blocking ring.

[0125] In some embodiments, for any group of populations, the data of the structural parameters corresponding to the group of populations are substituted into the error expression, and the sum of the differences between the compensation luminous flux and the loss luminous flux within the incident angle range of the incident light is calculated according to the obtained error expression, that is, the global cosine correction error corresponding to the group of populations is calculated, and the inverse of the obtained sum of differences is the population fitness of the group of populations. For the embodiment including the first expression, the first sub-expression, and the second sub-expression, for each group of populations, the first structural coefficient k1, the second structural coefficient k2, and the third structural coefficient k3 are calculated according to the data of the structural parameters corresponding to the group of populations, and then the error expression is obtained for calculation.

[0126] In some embodiments, performing population iteration includes but is not limited to mutation operations, selection operations, recombination operations, genotype to phenotype, or offspring insertion into a parent population.

[0127] By solving the objective function, a data set is obtained when the objective function takes the minimum value. In some embodiments, for each group of data in the data set, the critical angle corresponding to the group of data is calculated, and the change trend of the critical angle is obtained according to the critical angle corresponding to each group of data in the data set, and the critical angle is the minimum incident angle when the incident light is incident on the cosine corrector body and the light blocking ring will block the incident light. Based on the obtained critical angle change trend, the designer can understand the effect of the light blocking ring on the cosine corrector. For example, refer to Figure 6, which is a curve of the change of the critical angle obtained in the cosine corrector optimization design method of an embodiment. It can be seen that the critical angles are all above 75°, which shows that the light blocking ring works at a larger angle, and the critical angle when the cosine correction effect is optimal is basically around 75°.

[0128] In some embodiments, solving the objective function to obtain the data set that minimizes the value of the objective function may include: after determining the size of the sensing surface of the detector and the distance from the lower surface of the cosine corrector body to the sensing surface of the detector, solving the objective function to obtain the data set that minimizes the value of the objective function.

[0129] Further based on the data set, determining the data of the structural parameters of the cosine corrector may include: obtaining a first relationship and a second relationship based on the data set, the first relationship describing the relationship between the side dimension of the cosine corrector body that is spaced apart from the inner surface of the light-blocking ring and the upper surface dimension of the cosine corrector body, and the second relationship describing the relationship between the spacing distance from the side of the cosine corrector body to the inner surface of the light-blocking ring and the upper surface dimension of the cosine corrector body, so as to use the first relationship and the second relationship to determine the upper surface dimension of the cosine corrector body, the side dimension of the cosine corrector body that is spaced apart from the inner surface of the light-blocking ring, and the spacing distance from the side of the cosine corrector body to the inner surface of the light-blocking ring.

[0130] After determining the size of the sensing surface of the detector and the distance from the lower surface of the cosine corrector body to the sensing surface of the detector, for cosine corrector bodies of different sizes, the side dimensions of the interval between the cosine corrector body and the inner surface of the light-blocking ring can be determined according to the first relationship, and the interval distance from the side of the cosine corrector body to the inner surface of the light-blocking ring can be determined according to the second relationship.

[0131] The first relational expression or the second relational expression can be obtained by fitting each group of data in the data set, and the fitting method includes but is not limited to the least squares fitting, polynomial fitting or spline interpolation fitting method. In some embodiments, the first relational expression is a linear relational expression, and the second relational expression is a linear relational expression. Exemplarily, the data of the discrete points obtained by calculation are fitted with the least squares method to obtain two smooth straight lines, as shown in FIG7 , FIG7 is a curve corresponding to the first relational expression and a curve corresponding to the second relational expression obtained in the cosine corrector optimization design method of an embodiment, and the fitting functions are respectively expressed as , .

[0132] The cosine corrector to which this embodiment is applied can be shown in reference to FIG2. The function of the cosine corrector body 2 is to correct incident light of different incident angles in real time. For example, if the incident light is sunlight at different angles, white diffusion glass with better diffuse transmission characteristics can be selected as the diffuse transmission material to form the cosine corrector body 2, so that the incident light passing through it can better meet the cosine response, thereby reducing the radiation measurement error. The function of the light-blocking ring 1 is to meet the theoretical requirement that the radiation energy received by the detector 4 is 0 when the incident angle is 90°. The height of the light-blocking ring 1 and the cosine corrector body 2 is set to be flush so that the angular response detected by the detector 4 is closer to the ideal cosine response at all zenith angles.

[0133] By applying the cosine corrector optimization design method of this embodiment, after determining the basic dimensions of the atmospheric downlink radiation measurement sensor, based on the analytical model and algorithm optimization results derived above, the structural parameters when the global cosine error is minimum can be quickly calculated, thereby completing the optimization design of the cosine corrector.

[0134] This method constructs a theoretical analytical model for structural optimization design of the cosine corrector using a light-blocking ring structure, and proposes a parameter solution algorithm. For atmospheric downlink radiation measurement sensors of any size, the structural parameters of the cosine corrector when the global cosine error is minimum can be quickly calculated. For atmospheric downlink radiation measurement sensors of any size, the optimal design scheme of the cosine corrector can be quickly given, avoiding the time and cost loss of simulation experiments. This is one of the biggest advantages of model-based analytical calculations over numerical simulations. This method designs a cosine corrector based on the theoretical model of optical radiation transmission, which can output more accurate atmospheric downlink radiation measurement data. With the support of the theoretical model, the designed cosine corrector can improve the accuracy of the output results of the atmospheric downlink radiation measurement sensor, thereby providing higher quality correction data for UAV spectral remote sensing.

[0135] This embodiment also provides a cosine corrector optimization design device, including:

[0136] Memory for storing computer programs;

[0137] A processor is used to implement the steps of the cosine corrector optimization design method as described in any of the above embodiments when executing the computer program.

[0138] The cosine corrector optimization design device of this embodiment realizes the optimization design of the cosine corrector, and can make the cosine correction error of the cosine corrector meet the requirements.

[0139] This embodiment also provides a cosine corrector, including a cosine corrector body and a light-blocking ring, wherein the cosine corrector body is disposed in the light-blocking ring, so that incident light is incident on the upper surface of the cosine corrector body or the side surface of the cosine corrector body spaced from the inner surface of the light-blocking ring, and then incident on a detector after passing through the cosine corrector body, wherein the cosine corrector is obtained by using the cosine corrector optimization design method described in any one of the above embodiments. The cosine corrector of this embodiment can make the cosine correction error meet the requirements.

[0140] The above is a detailed introduction to the cosine corrector and its optimization design method and device provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A cosine corrector optimization design method, characterized in that: The cosine corrector comprises a cosine corrector body and a light-blocking ring, wherein the cosine corrector body is arranged in the light-blocking ring, so that the incident light is incident on the upper surface of the cosine corrector body or the side surface of the cosine corrector body which is spaced from the inner surface of the light-blocking ring, and then passes through the cosine corrector body and is incident on the detector; The cosine corrector optimization design method comprises: Determining structural parameters of the cosine corrector that affect the cosine correction error; Obtaining a first expression, wherein the first expression describes the relationship between the lost light flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the lost light flux is the light flux lost in the process of the incident light being incident on the upper surface of the cosine corrector body, passing through the cosine corrector body and being incident on the detector; Obtaining a second expression, wherein the second expression describes the relationship between the compensation luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the compensation luminous flux is the luminous flux of the incident light incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector; An error expression is obtained according to the first expression and the second expression, wherein the error expression describes the relationship between the difference between the compensated luminous flux and the lost luminous flux, the incident angle of the incident light, and the structural parameters of the cosine corrector, and the error expression is used to determine the data of the structural parameters of the cosine corrector so that the obtained cosine corrector, according to the error expression, the sum of the differences between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light, calculated to meet the requirements.

2. The cosine corrector optimization design method according to claim 1, characterized in that: The data of the structural parameters of the cosine corrector are determined by using the error expression, so that the obtained cosine corrector, the sum of the differences between the compensation luminous flux and the loss luminous flux within the incident angle range of the incident light calculated according to the error expression, meets the requirements including: Using the error expression, an objective function is established, wherein the objective function describes the sum of differences between the compensation luminous flux and the loss luminous flux within the incident angle range of the incident light; Solving the objective function to obtain a data set that minimizes the value of the objective function, wherein the data set includes multiple sets of data of the structural parameters; According to the data set, data of the structural parameters of the cosine corrector are determined.

3. The cosine corrector optimization design method according to claim 2, characterized in that: The structural parameters include the size of the upper surface of the cosine corrector body, the side size of the space between the cosine corrector body and the inner surface of the light-blocking ring, and the spacing distance from the side of the cosine corrector body to the inner surface of the light-blocking ring; Solving the objective function and obtaining a data set that minimizes the value of the objective function includes: After determining the size of the sensing surface of the detector and the distance from the lower surface of the cosine corrector body to the sensing surface of the detector, solving the objective function to obtain the data set that minimizes the value of the objective function; According to the data set, the data for determining the structural parameters of the cosine corrector includes: A first relational expression and a second relational expression are obtained according to the data set, wherein the first relational expression describes the relationship between the side dimension of the cosine corrector body spaced apart from the inner surface of the light-blocking ring and the upper surface dimension of the cosine corrector body, and the second relational expression describes the relationship between the spacing distance from the side of the cosine corrector body to the inner surface of the light-blocking ring and the upper surface dimension of the cosine corrector body, so as to determine the upper surface dimension of the cosine corrector body, the side dimension of the cosine corrector body spaced apart from the inner surface of the light-blocking ring, and the spacing distance from the side of the cosine corrector body to the inner surface of the light-blocking ring by using the first relational expression and the second relational expression.

4. The cosine corrector optimization design method according to claim 2, characterized in that: Using the error expression to establish the objective function includes: A plurality of incident angles are selected within the incident angle range of the incident light, and the error expression is used to obtain the sum of the differences between the compensated luminous flux and the lost luminous flux corresponding to the plurality of incident angles, so as to establish the objective function.

5. The cosine corrector optimization design method according to claim 2, characterized in that: Solving the objective function includes: Step S1: randomly generate N groups of chromosomes, corresponding to N groups of populations, each group of populations corresponding to a group of data of the structural parameters; Step S2: Calculate the population fitness for each group of populations, wherein the population fitness is calculated based on the error expression and the data of the structural parameters corresponding to the population; Step S3: Determine whether the value of the population fitness meets the requirement; Step S4: Perform population iteration to obtain a new offspring population, and increase the number of iterations by one; Step S5: Determine whether the number of iterations reaches the maximum number of iterations. If so, the data of the structural parameters corresponding to the population whose population fitness value meets the requirements is output as the output result; if the number of iterations does not reach the maximum number of iterations, enter step S2.

6. The cosine corrector optimization design method according to claim 5, characterized in that: Calculating population fitness includes: For any group of populations, the data of the structural parameters corresponding to this group of populations are substituted into the error expression, and the sum of the differences between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light is calculated according to the obtained error expression. The inverse of the obtained sum of differences is the population fitness of this group of populations.

7. The cosine corrector optimization design method according to claim 2, characterized in that: Also includes: For each group of data in the data set, the critical angle corresponding to the group of data is calculated, and the changing trend of the critical angle is obtained according to the critical angle corresponding to each group of data in the data set. The critical angle is the minimum incident angle at which the light blocking ring will block the incident light when the incident light enters the cosine corrector body.

8. The cosine corrector optimization design method according to claim 1, characterized in that: The second expression includes a first sub-expression and a second sub-expression; The first sub-expression describes the relationship between the first compensation luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the first compensation luminous flux is the luminous flux of the incident light with an incident angle less than the critical angle incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector; The second sub-expression describes the relationship between the second compensation luminous flux and the incident angle of the incident light and the structural parameters of the cosine corrector, wherein the second compensation luminous flux is the luminous flux of the incident light with an incident angle greater than the critical angle incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector; The critical angle is the minimum incident angle at which the light-blocking ring blocks the incident light when the incident light enters the cosine corrector body; The error expression includes a first error expression and a second error expression. The first error expression describes the relationship between the difference between the first compensating luminous flux and the lost luminous flux, the incident angle of the incident light, and the structural parameters of the cosine corrector. The second error expression describes the relationship between the difference between the second compensating luminous flux and the lost luminous flux, the incident angle of the incident light, and the structural parameters of the cosine corrector.

9. A cosine corrector optimization design device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the cosine corrector optimization design method as claimed in any one of claims 1 to 8 when executing the computer program.

10. A cosine corrector, characterized in that: The invention comprises a cosine corrector body and a light-blocking ring, wherein the cosine corrector body is arranged in the light-blocking ring so that incident light is incident on the upper surface of the cosine corrector body or the side surface of the cosine corrector body spaced from the inner surface of the light-blocking ring, and is incident on a detector after passing through the cosine corrector body. The cosine corrector is obtained by adopting the cosine corrector optimization design method according to any one of claims 1 to 8.

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