Cosine corrector and optimization design method and device thereof

Abstract

The application 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. The method comprises the following steps: obtaining a first expression and a second expression. The first expression is about the loss light flux of incident light incident to the upper surface of the cosine corrector body. The second expression is about the compensation light flux of the incident light incident to the side surface of the cosine corrector body. An error expression is obtained. The error expression describes the relationship between the difference between the compensation light flux and the loss light flux and the incident angle of the incident light and the structural parameters of the cosine corrector. The data of the structural parameters of the cosine corrector are determined by using the error expression. The sum of the difference between the compensation light flux and the loss light flux in the incident angle range of the incident light calculated according to the error expression meets the requirements. The application realizes the optimization design of the cosine corrector, and the cosine correction error of the cosine corrector can meet the requirements.

Description

TECHNICAL FIELD

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

[0002] As a convenient flight platform, the unmanned aerial vehicle (UAV) is more and more widely used in the field of low-altitude remote sensing. The UAV low-altitude spectral technology, which combines the UAV technology and the spectral remote sensing technology, has important application value and is the research focus in the current quantitative remote sensing field. The data accuracy is the prerequisite and basis for the application of quantitative remote sensing data. Studies have shown that the temporal and spatial variation of atmospheric downward radiation is one of the main factors affecting the accuracy of low-altitude spectral remote sensing data. By installing an atmospheric downward radiation measurement sensor on the back of the UAV to synchronously detect the variation of atmospheric downward irradiance and using the measurement results for data correction, the radiation measurement error caused by the variation of atmospheric downward radiation can be effectively reduced.

[0003] The atmospheric downward radiation measurement sensor used in the UAV spectral remote sensing mainly includes a cosine corrector, a spectral selector and a photoelectric detector. The cosine response characteristic of the cosine corrector is the main factor affecting the measurement accuracy of the atmospheric downward radiation. The cosine corrector is an optical diffuser installed before the photoelectric detector to realize the capture of light intensity signals within a 180° field of view through the scattering of the material. The downward radiation measurement sensor with ideal cosine correction function has a radiation response complying with the Lambert cosine law, i.e. the radiation response varies with the cosine of the angle between the light incident direction and the normal direction of the detection surface, which is expressed as:

[0004] ;

[0005] In the formula, Res represents the radiation response, θ represents the angle between the light incident direction and the normal direction of the detection surface, and Res0 represents the radiation response when the light is perpendicular to the detection surface. The correction effect of the actual cosine corrector will have a certain degree of deviation compared with the Lambert cosine curve, which is called the cosine correction error. In order to improve the radiation correction accuracy of the spectral remote sensing data, the cosine corrector needs to be optimized to reduce the cosine correction error. At present, there are few studies on the optimization of the cosine corrector, which leads to the fact that the measurement accuracy of the atmospheric downward radiation cannot meet the demand of the radiation correction accuracy of the quantitative remote sensing. SUMMARY

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

[0007] To achieve the above purpose, the present application provides the following technical solutions:

[0008] A cosine corrector optimization design method, 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 to an upper surface of the cosine corrector body or a side surface of the cosine corrector body having a spacing from an inner surface of the light blocking ring, and then is incident to a detector after passing through the cosine corrector body; the cosine corrector optimization design method comprising:

[0009] determining structure parameters of the cosine corrector affecting cosine correction error;

[0010] obtaining a first expression describing a relationship between loss light flux and incident angle of incident light, the structure parameters of the cosine corrector, the loss light flux being light flux lost in a process that incident light is incident to an upper surface of the cosine corrector body, passes through the cosine corrector body and is incident to the detector;

[0011] obtaining a second expression describing a relationship between compensation light flux and incident angle of incident light, the structure parameters of the cosine corrector, the compensation light flux being light flux that incident light is incident to a side surface of the cosine corrector body, passes through the cosine corrector body and is incident to the detector;

[0012] obtaining an error expression from the first expression and the second expression, the error expression describing a relationship between a difference between the compensation light flux and the loss light flux and the incident angle of incident light, the structure parameters of the cosine corrector, and determining data of the structure parameters of the cosine corrector by using the error expression, so that the obtained cosine corrector satisfies a requirement that a sum of the difference between the compensation light flux and the loss light flux in a range of the incident angle of incident light calculated according to the error expression meets the requirement.

[0013] Optionally, the determining of the data of the structure parameters of the cosine corrector by using the error expression, so that the obtained cosine corrector satisfies a requirement that a sum of the difference between the compensation light flux and the loss light flux in a range of the incident angle of incident light calculated according to the error expression meets the requirement comprises:

[0014] establishing an objective function by using the error expression, the objective function describing the sum of the difference between the compensation light flux and the loss light flux in the range of the incident angle of incident light;

[0015] solving the objective function to obtain a data set at which the objective function takes a minimum value, the data set comprising multiple groups of data of the structure parameters;

[0016] determining the data of the structure parameters of the cosine corrector according to the data set.

[0017] Optionally, the structural parameters include the upper surface dimension of the cosine corrector body, the side dimension of the cosine corrector body with a gap between the inner surface of the light-blocking ring and the cosine corrector body, and the distance between the side of the cosine corrector body and the inner surface of the light-blocking ring.

[0018] Solving the objective function to obtain the dataset 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, the objective function is solved to obtain the dataset that minimizes the value of the objective function.

[0020] The data used to determine the structural parameters of the cosine corrector based on the dataset includes:

[0021] Based on the dataset, a first relation and a second relation are obtained. The first relation describes the relationship between the side dimension of the cosine corrector body that is spaced from the inner surface of the light-blocking ring and the top surface dimension of the cosine corrector body. The second relation describes the relationship between the distance between the side dimension of the cosine corrector body and the inner surface of the light-blocking ring and the top surface dimension of the cosine corrector body. The top surface dimension of the cosine corrector body, the side dimension of the cosine corrector body that is spaced from the inner surface of the light-blocking ring, and the distance between the side dimension of the cosine corrector body and the inner surface of the light-blocking ring are determined using the first relation and the second relation.

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

[0023] Multiple incident angles are selected within the incident angle range of the incident light. Using the error expression, the sum of the differences between the compensated luminous flux and the lost luminous flux corresponding to the multiple incident angles is obtained to establish the objective function.

[0024] Optionally, solving the objective function includes:

[0025] Step S1: Randomly generate N sets of chromosomes, each corresponding to one of the N populations, and each population corresponds to a set of structural parameter data;

[0026] Step S2: Calculate the population fitness for each population group. 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 fitness value of the population meets the requirements;

[0028] Step S4: Perform population iteration to obtain a new offspring population, and increment the iteration count by one;

[0029] Step S5: Determine whether the number of iterations has reached the maximum number of iterations. If the number of iterations has reached the maximum number of iterations, then the data of the structural parameters corresponding to the population whose fitness value meets the requirements are used as the output result; if the number of iterations has not reached the maximum number of iterations, then proceed to step S2.

[0030] Optionally, calculating population fitness includes:

[0031] For any population group, the data of the structural parameters corresponding to this population group are substituted into 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 is calculated based on the obtained error expression. The reciprocal of the obtained sum of differences is the population fitness of this population group.

[0032] Optionally, it also includes:

[0033] For each set of data in the dataset, the critical angle corresponding to this set of data is calculated, and the trend of the change of the critical angle is obtained according to the critical angle corresponding to each set of data in the dataset. The critical angle is the minimum incident angle when the light blocking ring blocks the incident light when the incident light is incident on the body of the cosine corrector.

[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 light flux and the incident angle of the incident light and the structural parameters of the cosine corrector. The first compensation light flux is the light flux of incident light with an incident angle less than the critical angle that is incident on the side of the cosine corrector body, passes through the cosine corrector body and is incident on the detector.

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

[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 compensated luminous flux and the lost luminous flux and 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 compensated luminous flux and the lost luminous flux and 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, used to store computer programs;

[0041] A processor, used to implement the steps of the cosine corrector optimization design method as described in any of the preceding claims when executing the computer program.

[0042] A cosine corrector includes a cosine corrector body and a light-blocking ring. The cosine corrector body is disposed within the light-blocking ring, such that incident light is incident on the upper surface of the cosine corrector body or on a side of the cosine corrector body that is spaced apart from the inner surface of the light-blocking ring, and after passing through the cosine corrector body, is incident on a detector. The cosine corrector is obtained using any of the cosine corrector optimization design methods described above.

[0043] As can be seen from the above technical solution, the cosine corrector optimization design method and apparatus provided by the present invention includes a cosine corrector body and a light-blocking ring, with the cosine corrector body disposed within the light-blocking ring. The method includes: obtaining a first expression and a second expression, where the first expression pertains to the luminous flux loss of incident light incident on the upper surface of the cosine corrector body, and the second expression pertains to the luminous flux compensation of incident light incident on the side surface of the cosine corrector body; obtaining an error expression, where the error expression describes the relationship between the difference between the compensation luminous flux and the luminous flux loss and the incident angle of the incident light and the structural parameters of the cosine corrector; and using the error expression to determine the structural parameters of the cosine corrector, ensuring that the sum of the differences between the compensation luminous flux and the luminous flux loss within the incident angle range of the incident light, calculated according to the error expression, meets the requirements. The cosine corrector optimization design method and apparatus of the present invention achieves optimized design of the cosine corrector, ensuring that the cosine correction error of the cosine corrector meets the requirements.

[0044] The present invention provides a cosine corrector that enables the cosine correction error to meet the requirements. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 A flowchart illustrating an optimized design method for a cosine corrector according to an embodiment of the present invention;

[0047] Figure 2 A schematic diagram of a cosine corrector to which the cosine corrector optimization design method provided in an embodiment of the present invention is applied;

[0048] Figure 3 A schematic diagram illustrating the principle of obtaining the second expression through integration in the cosine corrector optimization design method provided in an embodiment of the present invention;

[0049] Figure 4 A flowchart of a cosine corrector optimization design method provided in another embodiment of the present invention;

[0050] Figure 5 This is a flowchart illustrating the method for optimizing the design of a cosine corrector according to an embodiment of the present invention, which involves solving the objective function.

[0051] Figure 6 The curve showing the change of the critical angle obtained in the cosine corrector optimization design method according to an embodiment of the present invention;

[0052] Figure 7 The first relational curve and the second relational curve are obtained in the cosine corrector optimization design method according to an embodiment of the present invention.

[0053] The reference numerals in the accompanying drawings include:

[0054] 1-Brightening ring, 2-Cosine corrector body, 3-Housing, 4-Detector. Detailed Implementation

[0055] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0056] This embodiment provides a cosine corrector optimization design method. The cosine corrector includes a cosine corrector body and a light-blocking ring. The cosine corrector body is disposed inside the light-blocking ring, such that incident light is incident on the upper surface of the cosine corrector body or on the side of the cosine corrector body that is spaced apart from the inner surface of the light-blocking ring, and then passes through the cosine corrector body and enters the detector.

[0057] For reference Figure 1 , Figure 1 A flowchart of a cosine corrector optimization design method provided for one embodiment is 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 it passes through the cosine corrector and the radiation response that satisfies Lambert's cosine law.

[0060] For this cosine corrector, 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 some light energy is lost when the light passes through the cosine corrector body, such as absorption loss, refraction loss, or reflection loss of the cosine corrector body, cosine correction error will occur.

[0061] To address this, in this cosine corrector, the incident light can be incident on the side of the cosine corrector body that is spaced apart from the inner surface of the light-blocking ring, and after passing through the cosine corrector body, it is incident on the detector. This portion 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 this cosine corrector can meet the requirements.

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

[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 when the incident light is incident on the upper surface of the cosine corrector body, passes through the cosine corrector body, and is incident on the detector.

[0064] Based on the principle of light radiation transmission during the process of incident light hitting the upper surface of the cosine corrector body, passing through the cosine corrector body, and then 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 during the process of incident light hitting the upper surface of the cosine corrector body, passing through the cosine corrector body, and then 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 incident on the side of the cosine corrector body, passing through the cosine corrector body and incident on the detector.

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

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

[0068] S14: Obtain an error expression based on the first expression and the second expression. 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. The data of the structural parameters of the cosine corrector are determined using the error expression, so that 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 according to the error expression, meets the requirements of the obtained cosine corrector.

[0069] For this cosine corrector, the difference between the compensated luminous flux and the lost luminous flux can be considered as the cosine correction error of this cosine corrector. The established error expression can be considered as a mathematical model describing the cosine correction error of this cosine corrector. The incident angle range refers to the range defined by the minimum and maximum incident angles 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 concerns the lost luminous flux of incident light incident on the upper surface of the cosine corrector body, and the second expression concerns the compensated luminous flux of incident light incident on the side surface of the cosine corrector body. An error expression is then obtained, describing 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. Thus, a theoretical mathematical model is established for the cosine correction error of this cosine corrector, and the structural parameter data of the cosine corrector are determined. This achieves the optimized design of the cosine corrector, ensuring that the cosine correction error of the cosine corrector meets the requirements.

[0071] In some implementations, the upper surface of the cosine corrector body is flush with the end face of the light-blocking ring, thus making the angular response detected by the detector closer to the ideal cosine response at all zenith angles. The end face of the light-blocking ring refers to the surface of the ring on the side where the incident light is incident. See, for example, [reference needed]. Figure 2 , Figure 2 The figure shows a schematic diagram of a cosine corrector to which the cosine corrector optimization design method provided in one embodiment is applied. The cosine corrector includes a cosine corrector body 2 and a light-blocking ring 1. The cosine corrector body 2 is disposed inside the light-blocking ring 1. There is a gap between the side of the cosine corrector body 2 near the incident light and the inner surface of the light-blocking ring 1. This side can be referred to as the exposed side of the cosine corrector body 2.

[0072] In some embodiments, structural parameters include the upper surface dimensions of the cosine corrector body 2, the side dimensions of the cosine corrector body 2 spaced from the inner surface of the light-blocking ring 1, and the distance between the side surface of the cosine corrector body 2 and the inner surface of the light-blocking ring 1. Structural parameters may also include the sensing surface dimensions of the detector 4 and the distance between the lower surface of the cosine corrector body 2 and the sensing surface of the detector 4. Examples can be found in conjunction with reference to [reference needed]. Figure 2 If the cross-section of the cosine corrector body 2 is circular, then... Figure 2 The structural parameters of the cosine corrector shown may include: the upper surface radius R of the cosine corrector body 2, the side height h of the cosine corrector body 2 with a gap between it 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 sensing surface radius r1 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 implementations, the first expression may be represented as: Where L1 represents the luminance loss of incident light after passing through the cosine corrector body onto the upper surface of the cosine corrector body, and k1 represents the first structural coefficient, which is related to the structural parameters of the cosine corrector. Figure 2 The cosine corrector shown has a first structural coefficient that is related to the upper surface size of the cosine corrector body, the sensing surface size 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] The light energy detected after the incident light passes through the upper surface of the cosine corrector body is calculated. The luminous flux loss of sunlight incident through the upper surface of the cosine corrector body due to internal absorption and reflection is expressed as:

[0076] ;

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

[0078] From the optical formula The brightness lost through its internal processes 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. Specifically, according to E = E0 * cosθ, S=πR 2 The formula for calculating L1 is obtained above.

[0081] Ignoring measurement errors introduced by transmission losses within the cosine corrector mounting structure, after incident light reaches the upper surface of the cosine corrector body, passes through the internal structure of the cosine corrector, and exits, the detector detects the lost luminous flux. ,in:

[0082] .

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

[0084] In some implementations, obtaining the second expression includes: according to the differential formula of luminous flux. By performing a surface integral on 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, the second expression is obtained, which is expressed as:

[0085] (1)

[0086] Where L represents luminance, K represents the structure coefficient, i represents the azimuth angle, l represents the illumination 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 with a gap, r1 represents the sensing surface radius of the detector, and Ω represents the solid angle of luminous flux.

[0087] Examples can be combined with references Figure 3 , Figure 3 This is a schematic diagram illustrating the principle of obtaining the second expression through integration in a cosine corrector optimization design method provided in one embodiment. The optical flux of 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 as follows. Figure 3 As shown in the figure, α represents the aperture angle of the incident light range on the side corresponding to the sensing surface of the detector.

[0088] According to the differential formula of luminous flux The detected side light intake is obtained by performing a surface integral on the side light intake, and is expressed as:

[0089] .

[0090] In some implementations, the second expression includes a first subexpression and a second subexpression;

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

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

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

[0094] Accordingly, 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 compensated luminous flux and the lost luminous flux and 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 compensated 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 incident light with an incident angle less than the critical angle is incident on the cosine corrector body, the baffle ring does not block the incident light, and the incident light can directly enter the upper surface and exposed side of the cosine corrector body (the exposed side is the side of the cosine corrector body with a gap between it and the inner surface of the baffle ring). When the incident angle of the incident light is greater than the critical angle, the incident light can directly enter the upper surface of the cosine corrector body, but due to the baffle ring, the exposed side of the cosine corrector body cannot be illuminated by the incident light. In this case, the baffle ring will block the incident light.

[0096] For reference Figure 4 , Figure 4 The flowchart of a cosine corrector optimization design method provided in another embodiment is shown in the figure. Before establishing the first sub-expression and the second sub-expression, the critical angle θ0 can be obtained by analysis. The critical angle θ0 is related to the exposed side dimension of the cosine corrector body and the distance between the exposed side 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 of the cosine corrector body is completely 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 body. The calculation formula for the critical angle θ0 is as follows:

[0097] .

[0098] exist Figure 4 In the diagram, the exposed height represents the exposed side dimension of the cosine corrector body, and the slot width represents the distance between the exposed side of the cosine corrector body and the inner surface of the light-blocking ring.

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

[0100] .

[0101] Where k2 represents the second structural coefficient, 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 with a gap, and r1 represents the sensing surface radius of the detector.

[0102] And from the optical formula and The illuminance of light incident on the side of the cosine corrector and emitted from it can be expressed as: Among them, Φ ⊥ ρ' represents the luminous flux incident on the upper surface of the cosine corrector body when the incident light is incident perpendicularly, 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 illumination height.

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

[0104] .

[0105] The first sub-expression can be represented as: Φ = k2L. By obtaining the relationship between the deviation and the above parameters, we obtain the first error expression: .

[0106] When θ0 < θ < 90°, the illumination height That is, the range of the side of the cosine corrector body that can be illuminated by 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, as well as the incident angle θ. In this scenario, according to the differential formula of luminous flux and formula (1), we can obtain:

[0107] .

[0108] The second sub-expression can be represented as: Φ = k3L, where k3 represents the third structure coefficient. The second error expression can then be obtained by solving for: .

[0109] In some implementations, the structural parameters of the cosine corrector can be determined using the error expression through the following process, such that 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 according to the error expression, meets the requirements. This includes the following steps:

[0110] S141: Establish an objective function using the error expression, the objective function describing the sum of the differences between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light;

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

[0112] S143: Based on the dataset, determine the structural parameters of the cosine corrector.

[0113] For this 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 can be considered as the global cosine correction error of the cosine corrector.

[0114] Given the objective function, solve for it to obtain multiple sets of structural parameter data for the cosine corrector. The obtained structural parameter data minimizes the objective function. Further, based on the dataset, determine the structural parameters of the cosine corrector to be designed.

[0115] In this embodiment, an objective function describing the global cosine correction error of the cosine corrector is established using an error expression. Multiple sets of structural parameter data of the cosine corrector are obtained by solving the objective function. Then, the structural parameters of the cosine corrector are determined based on these multiple sets of structural parameter data. In this way, a theoretical mathematical model is established for the cosine correction error of this cosine corrector, and the structural parameter data of the cosine corrector are determined. This allows for the acquisition of the optimal structural design and the rapid provision of an optimized design scheme for the cosine corrector.

[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 compensated luminous flux and the lost luminous flux corresponding to the multiple incident angles, thereby establishing the objective function. In some embodiments, multiple incident angles can be selected at equal angular intervals within the range from the minimum incident angle to the maximum incident angle of the incident light. In this embodiment, the angular 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 pattern reflected by the differences corresponding to the multiple incident angles. For example, the angular interval can be selected as 5°. Theoretically, multiple incident angles can also be selected within the range from the minimum incident angle to the maximum incident angle according to other angular intervals to calculate the sum of the differences. However, since the magnitude of the error is inversely proportional to the incident angle, the angular interval should not be too large. At the same time, it is also necessary to reflect the error pattern presented by the multiple incident angles. Therefore, 5° is more appropriate. In other embodiments, the objective function can be obtained by integrating the error expression over the range of the minimum to the maximum incident angle of the incident light, but this embodiment involves a large amount of computation.

[0117] The established objective function describes the sum of the differences between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light. In other words, the established objective function is the sum of the absolute values ​​of the differences between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light. For implementations that select multiple incident angles within the incident angle range of the incident light to establish the objective function using an error expression, the established objective function describes the sum of the differences corresponding to the multiple incident angles. In other words, the established objective function is the sum of the absolute values ​​of the differences corresponding to the multiple incident angles. In some implementations, the objective function can be established by summing the absolute values ​​of the differences corresponding to each of the multiple incident angles. Alternatively, the objective function can be established by summing the squares of the differences corresponding to each of the multiple incident angles. For example, with a minimum incident angle of 0° and a maximum incident angle of 90°, multiple incident angles can be selected from 0° to 90°, and the corresponding error values ​​y can be summed. Considering the global error, the objective function can be simply expressed as: .

[0118] In some implementations, a genetic algorithm can be used to solve the objective function; see reference. Figure 5 , Figure 5 This is a flowchart illustrating the objective function solution for a cosine corrector optimization design method according to one embodiment. Solving the objective function includes the following steps:

[0119] Step S1: Randomly generate N sets of chromosomes, each corresponding to one of the N populations, and each population corresponds to a set of structural parameter data;

[0120] Step S2: Calculate the population fitness for each population group. 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 fitness value of the population meets the requirements;

[0122] Step S4: Perform population iteration to obtain a new offspring population, and increment the iteration count by one;

[0123] Step S5: Determine whether the number of iterations has reached the maximum number of iterations. If the number of iterations has reached the maximum number of iterations, then the data of the structural parameters corresponding to the population whose fitness value meets the requirements are used as the output result; if the number of iterations has not reached the maximum number of iterations, then proceed to step S2.

[0124] In some implementations, for each group of chromosomes, the values ​​of the structural parameters corresponding to each population group can be obtained using binary encoding. Exemplary structural parameters include: the upper surface radius R of the cosine corrector body 2, the side height h of the cosine corrector body 2 with a gap between it 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.

[0125] In some implementations, for any given population, the error expression is substituted with the structural parameter data corresponding to that population. 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 based on the obtained error expression; that is, the global cosine correction error corresponding to that population is calculated. The reciprocal of the obtained sum of differences is the population fitness of that population. For implementations including a first expression, a first sub-expression, and a second sub-expression, for each population, a first structural coefficient k1, a second structural coefficient k2, and a third structural coefficient k3 are calculated based on the structural parameter data corresponding to that population, and then the error expression is obtained for calculation.

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

[0127] By solving the objective function, a dataset that minimizes the objective function's value is obtained. In some implementations, for each set of data in the dataset, the critical angle corresponding to that set is calculated. Based on the critical angles corresponding to each set of data in the dataset, the trend of the critical angle's change is obtained. The critical angle is the minimum incident angle at which the light-blocking ring blocks the incident light when it strikes the cosine corrector body. Based on the obtained trend of the critical angle's change, designers can understand the effect of the light-blocking ring on the cosine corrector. An example can be referred to... Figure 6 , Figure 6 The curves showing the change of critical angles obtained from the cosine corrector optimization design method in one embodiment are shown. It can be seen that the critical angles are all above 75°, indicating that the light-blocking ring works at relatively large angles, and the critical angle at which the cosine correction effect is optimal is approximately 75°.

[0128] In some implementations, solving the objective function to obtain the dataset that minimizes the value of the objective function may include: after determining the sensing surface size 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 dataset that minimizes the value of the objective function.

[0129] Further, based on the dataset, the data used to determine the structural parameters of the cosine corrector may include: obtaining a first relation and a second relation based on the dataset. The first relation describes the relationship between the side dimension of the cosine corrector body that is spaced from the inner surface of the light-blocking ring and the top surface dimension of the cosine corrector body. The second relation describes the relationship between the distance between the side dimension of the cosine corrector body and the inner surface of the light-blocking ring and the top surface dimension of the cosine corrector body. The top surface dimension of the cosine corrector body, the side dimension of the cosine corrector body that is spaced from the inner surface of the light-blocking ring, and the distance between the side dimension of the cosine corrector body and the inner surface of the light-blocking ring are determined using the first relation and the second relation.

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

[0131] A first or second relation can be obtained by fitting data from each group of data in the dataset. Fitting methods include, but are not limited to, least squares fitting, polynomial fitting, or spline interpolation fitting. In some implementations, both the first and second relations are linear. For example, least squares fitting is performed on the calculated discrete point data to obtain two smooth straight lines, such as... Figure 7 As shown, Figure 7 The first relational curve and the second relational curve obtained in the cosine corrector optimization design method of one embodiment are respectively expressed by the fitting function as follows: , .

[0132] The cosine corrector used in this embodiment can be found in the following reference. Figure 2 As shown, the function of the cosine corrector body 2 is to correct incident light at different incident angles in real time. For example, if the incident light is sunlight at different angles, white diffuser glass with good 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 better meets the cosine response, thereby reducing radiation measurement errors. The function of the light-blocking ring 1 is to ensure that, theoretically, the radiation energy received by the detector 4 is 0 when the incident angle is 90°. Setting the heights of the light-blocking ring 1 and the cosine corrector body 2 to be aligned is to make the angular response detected by the detector 4 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 down-current radiation measurement sensor, the structural parameters at the minimum global cosine error state can be quickly calculated based on the above-derived analytical model and algorithm optimization results, thereby completing the optimization design of the cosine corrector.

[0134] This method constructs a theoretical analytical model for the structural optimization design of a cosine corrector using a light-blocking ring structure and proposes a parameter solving algorithm. For atmospheric downlink radiometry sensors of arbitrary size, it can quickly calculate the structural parameters of the cosine corrector when the global cosine error is minimized. For atmospheric downlink radiometry sensors of arbitrary size, it can quickly provide an optimized design scheme for the cosine corrector, avoiding the time and cost losses wasted on simulation experiments. This is one of the biggest advantages of model-based analytical calculations compared to numerical simulations. Based on the theoretical model of optical radiation transfer, this method designs a cosine corrector that can output more accurate atmospheric downlink radiometry data. With the support of the theoretical model, the designed cosine corrector can improve the accuracy of the output results of atmospheric downlink radiometry sensors, thereby providing higher-quality calibration data for UAV spectral remote sensing.

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

[0136] Memory, used to store computer programs;

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

[0138] The cosine corrector optimization design device in this embodiment realizes the optimized design of the cosine corrector, which enables the cosine correction error of the cosine corrector to meet the requirements.

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

[0140] The cosine corrector and its optimized design method and apparatus provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A method for optimizing the design of a cosine corrector, characterized in that, The cosine corrector includes a cosine corrector body and a light-blocking ring. The cosine corrector body is disposed inside the light-blocking ring, such that incident light is incident on the upper surface of the cosine corrector body or on the side of the cosine corrector body that is spaced apart from the inner surface of the light-blocking ring, and then passes through the cosine corrector body and enters the detector. The cosine corrector optimization design method includes: The structural parameters affecting the cosine correction error of the cosine corrector are determined. The structural parameters include the upper surface dimension of the cosine corrector body, the side dimension of the cosine corrector body with a gap between the inner surface of the light-blocking ring and the cosine corrector body, and the gap distance from the side of the cosine corrector body to the inner surface of the light-blocking ring. A first expression is obtained, which describes the relationship between the light loss and the incident angle of the incident light and the structural parameters of the cosine corrector. The light loss is the light loss that occurs when the incident light is incident on the upper surface of the cosine corrector body, passes through the cosine corrector body and is incident on the detector. A second expression is obtained, which describes the relationship between the compensation light flux and the incident angle of the incident light and the structural parameters of the cosine corrector. The compensation light flux is 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. An error expression is obtained based on the first expression and the second expression. 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. The data of the structural parameters of the cosine corrector are determined using the error expression, so that 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 according to the error expression, meets the requirements of the cosine corrector.

2. The cosine corrector optimization design method according to claim 1, characterized in that, The structural parameters of the cosine corrector are determined using the error expression, such that 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 according to the error expression, satisfies the following requirements: An objective function is established using the error expression, which describes the sum of the differences between the compensated luminous flux and the lost luminous flux within the incident angle range of the incident light. Solve the objective function to obtain a dataset that minimizes the value of the objective function, the dataset including multiple sets of data for the structural parameters; Based on the dataset, the structural parameters of the cosine corrector are determined.

3. The cosine corrector optimization design method according to claim 2, characterized in that, Solving the objective function to obtain the dataset 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, the objective function is solved to obtain the dataset that minimizes the value of the objective function. The data used to determine the structural parameters of the cosine corrector based on the dataset includes: Based on the dataset, a first relation and a second relation are obtained. The first relation describes the relationship between the side dimension of the cosine corrector body that is spaced from the inner surface of the light-blocking ring and the top surface dimension of the cosine corrector body. The second relation describes the relationship between the distance between the side dimension of the cosine corrector body and the inner surface of the light-blocking ring and the top surface dimension of the cosine corrector body. The top surface dimension of the cosine corrector body, the side dimension of the cosine corrector body that is spaced from the inner surface of the light-blocking ring, and the distance between the side dimension of the cosine corrector body and the inner surface of the light-blocking ring are determined using the first relation and the second relation.

4. The cosine corrector optimization design method according to claim 2, characterized in that, Establishing the objective function using the aforementioned error expression includes: Multiple incident angles are selected within the incident angle range of the incident light. Using the error expression, the sum of the differences between the compensated luminous flux and the lost luminous flux corresponding to the multiple incident angles is obtained 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 sets of chromosomes, each corresponding to one of the N populations, and each population corresponds to a set of structural parameter data; Step S2: Calculate the population fitness for each population group. 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 fitness value of the population meets the requirements; Step S4: Perform population iteration to obtain a new offspring population, and increment the iteration count by one; Step S5: Determine whether the number of iterations has reached the maximum number of iterations. If the number of iterations has reached the maximum number of iterations, then the data of the structural parameters corresponding to the population whose fitness value meets the requirements are used as the output result; if the number of iterations has not reached the maximum number of iterations, then proceed to step S2.

6. The cosine corrector optimization design method according to claim 5, characterized in that, Calculating population fitness includes: For any population group, the data of the structural parameters corresponding to this population group are substituted into 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 is calculated based on the obtained error expression. The reciprocal of the obtained sum of differences is the population fitness of this population group.

7. The cosine corrector optimization design method according to claim 2, characterized in that, Also includes: For each set of data in the dataset, the critical angle corresponding to this set of data is calculated, and the trend of the change of the critical angle is obtained according to the critical angle corresponding to each set of data in the dataset. The critical angle is the minimum incident angle when the light blocking ring blocks the incident light when the incident light is incident on the body of the cosine corrector.

8. The cosine corrector optimization design method according to claim 1, characterized in that, The second expression includes a first subexpression and a second subexpression; The first sub-expression describes the relationship between the first compensation light flux and the incident angle of the incident light and the structural parameters of the cosine corrector. The first compensation light flux is the light flux of incident light with an incident angle less than the critical angle that is incident on the side of the cosine corrector body, passes through the cosine corrector body and is incident on the detector. The second sub-expression describes the relationship between the second compensation light flux and the incident angle of the incident light and the structural parameters of the cosine corrector. The second compensation light flux is the light flux of incident light with an incident angle greater than the critical angle that is incident on the side of the cosine corrector body, passes through the cosine corrector body, and is 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 is incident on the body of the cosine corrector. 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 compensated luminous flux and the lost luminous flux and 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 compensated luminous flux and the lost luminous flux and 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, used to store computer programs; A processor, configured to implement the steps of the cosine corrector optimization design method as described in any one of claims 1 to 8 when executing the computer program.

10. A cosine corrector, characterized in that, The device includes a cosine corrector body and a light-blocking ring. The cosine corrector body is disposed within the light-blocking ring, such that incident light is incident on the upper surface of the cosine corrector body or on a side of the cosine corrector body that is spaced apart from the inner surface of the light-blocking ring, and after passing through the cosine corrector body, it is incident on the detector. The cosine corrector is obtained by the cosine corrector optimization design method according to any one of claims 1 to 8.

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