Lens surface parameter acquisition method and device and blackboard lamp lens

Abstract

The application relates to the optical field and discloses a lens surface parameter acquisition method, a lens surface parameter acquisition device and a blackboard lamp lens. The lens surface parameter acquisition method comprises the following steps: obtaining a target parameter in the application of a lens. A target distribution curve is obtained through reverse fitting according to the target parameter. A corresponding relationship between a light source beam angle and the target distribution curve is established according to a preset algorithm and the target distribution curve. The surface parameter of the lens is calculated according to the target distribution curve and the corresponding relationship between the light source beam angle and the target distribution curve. The obtained lens can realize the target parameter in an application scene, effectively reduces a design cycle, improves design precision, reduces cost, and reduces the requirement for a designer.

Description

Technical Field

[0001] This application relates to the field of optics, and in particular to a method, apparatus for obtaining lens surface parameters, and a blackboard lamp lens. Background Technology

[0002] Blackboards are commonly used equipment for teaching or meetings. Blackboards set up indoors often require lighting to provide better results due to insufficient indoor lighting.

[0003] Currently, designing lenses for blackboard lights requires extensive and repeated optical simulations and adjustments based on past experience to meet design requirements. This demands high skill from designers, results in long design cycles, low accuracy, and high costs. Summary of the Invention

[0004] The main purpose of this application is to provide a method, device and blackboard lamp lens for obtaining lens surface parameters, which aims to solve the problems of high requirements for designers, long design cycle, poor accuracy and high cost when designing lenses.

[0005] In a first aspect, this application provides a method for obtaining lens surface parameters, comprising: obtaining target parameters for the lens application; obtaining a target light distribution curve through inverse fitting based on the target parameters; establishing a correspondence between the light source beam angle and the target light distribution curve based on a preset algorithm and the target light distribution curve; and calculating the lens surface parameters based on the target light distribution curve and the correspondence between the light source beam angle and the target light distribution curve.

[0006] In some implementations, the target parameters include the light intensity of the light source, the distance and height between the lens and the illuminated target, and the angle between at least one measurement point on the illuminated target and the light source.

[0007] The target light distribution curve is obtained by inverse fitting based on the target parameters, including: obtaining the target luminous intensity function of each measurement point by inverse fitting based on the distance and height between the lens and the irradiated target and the angle between at least one measurement point on the irradiated target and the light source. The curve of the target luminous intensity function of the measurement point in the coordinate system is the target light distribution curve.

[0008] In some implementations, a correspondence between the light source beam angle and the target light distribution curve is established based on a preset algorithm and the target light distribution curve. This includes: obtaining multiple sets of luminous intensity values ​​as a function of the target luminous intensity at the measurement point using a preset interpolation algorithm; fitting a function of the light source beam angle based on the multiple sets of luminous intensity values; and calculating the correspondence between the light source beam angle and the target light distribution curve based on the function of the light source beam angle and the function of the target luminous intensity at the measurement point.

[0009] In some implementations, the surface parameters of the lens are calculated based on the correspondence between the target light distribution curve, the light source beam angle and the target light distribution curve, including: according to Snell's law, the coordinates of each point on the lens surface are calculated based on the correspondence between the target light distribution curve, the light source beam angle and the target light distribution curve.

[0010] In some implementations, after obtaining the surface parameters of the lens, the method further includes: establishing a model of the lens based on the surface parameters of the lens.

[0011] Secondly, this application also provides a lens surface parameter acquisition device, comprising: an acquisition module for acquiring target parameters for lens application; a fitting module for inversely fitting the target parameters to obtain a target light distribution curve; the fitting module further for establishing a correspondence between the light source beam angle and the target light distribution curve based on a preset algorithm and the target light distribution curve; and a calculation module for calculating the lens surface parameters based on the target light distribution curve and the correspondence between the light source beam angle and the target light distribution curve.

[0012] In some implementations, the target parameters include the illumination intensity of the light source, the distance and height between the lens and the illuminated target, and the angle between at least one measurement point on the illuminated target and the light source. The fitting module is specifically used to inversely fit a function of the target luminous intensity at each measurement point based on the distance and height between the lens and the illuminated target, and the angle between at least one measurement point on the illuminated target and the light source. The curve of this function in the coordinate system is the target light distribution curve.

[0013] In some implementations, the fitting module is specifically used to obtain multiple sets of luminous intensity values ​​based on a function of the target luminous intensity at the measurement point using a preset interpolation algorithm. Based on these multiple sets of luminous intensity values, a function of the light source beam angle is fitted. Finally, based on the function of the light source beam angle and the function of the target luminous intensity at the measurement point, the correspondence between the light source beam angle and the target light distribution curve is calculated.

[0014] In some implementations, the calculation module is used to calculate the coordinates of each point on the lens surface based on Snell's law and the correspondence between the target light distribution curve, the light source beam angle and the target light distribution curve.

[0015] In some embodiments, the device also includes a modeling module for creating a model of the lens based on the lens's surface parameters.

[0016] Thirdly, this application also provides a blackboard light lens, the surface parameters of which are obtained according to the lens surface parameter acquisition method provided in the first aspect.

[0017] Fourthly, this application also provides a blackboard lamp, which includes the blackboard lamp lens provided in the third aspect.

[0018] The lens surface parameter acquisition method, apparatus, and blackboard lamp lens provided in this application obtain a target light distribution curve by inversely fitting the target parameters according to the target parameters in the lens application scenario. Then, based on a preset algorithm and the target light distribution curve, a correspondence between the light source beam angle and the target light distribution curve is established. Finally, the surface parameters of the lens are calculated based on the target light distribution curve and the correspondence between the light source beam angle and the target light distribution curve. The resulting lens can achieve the target parameters in the application scenario, effectively reducing the design cycle, improving design accuracy, reducing costs, and lowering the requirements for designers. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic flowchart illustrating a method for obtaining lens surface parameters provided in an embodiment of this application;

[0021] Figure 2 A schematic diagram illustrating an application scenario of a lens provided for an embodiment of this application;

[0022] Figure 3 This is a cross-sectional schematic diagram of a blackboard lamp lens provided in an embodiment of this application;

[0023] Figure 4 This is a schematic diagram of the structure of a lens surface parameter acquisition device provided in an embodiment of this application.

[0024] Legend: 200 - Blackboard lamp lens; 201 - First transmission surface; 202 - Second transmission surface; 203 - Third transmission surface; 204 - Total reflection surface; 205 - First incident surface; 206 - Second incident surface; 207 - Third incident surface; 208 - First connecting part; 209 - Second connecting part.

[0025] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0028] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0029] Figure 1 This is a schematic flowchart illustrating a method for obtaining lens surface parameters, provided as an embodiment of this application. Figure 2 This illustration shows an application scenario of a lens provided by an embodiment of this application. The method provided in this application can be applied to devices with computing capabilities, such as computers and servers. In this application, the acquisition of surface parameters of a blackboard lamp lens is used as an example for explanation. In this application, illuminance refers to light intensity, represented by E and measured in lux (lx); luminous intensity refers to luminous intensity, represented by I and measured in candela (cd); luminous flux refers to luminous flux, represented by φ and measured in lumens (lm).

[0030] In some implementation methods, please refer to Figure 1 Methods for obtaining lens surface parameters include:

[0031] S110. Obtain the target parameters when the lens is applied.

[0032] In some implementations, the design of blackboard light lenses requires that the illuminance at multiple measurement points on the blackboard after illumination by the blackboard light meets national regulations. For example, according to the "T / JYBZ 005-2018 Technical Specification for Lighting in Primary and Secondary School Classrooms," the standard blackboard size is 1200mm*4000mm, the blackboard illuminance is ≥500lx, and the uniformity U0 is ≥0.80. That is, the target parameters are blackboard illuminance ≥500lx and uniformity U0 ≥0.80.

[0033] In some implementations, the blackboard can be divided into multiple 400mm x 400mm squares; that is, a standard blackboard is divided into three parts: upper, middle, and lower, each part consisting of 10 horizontally arranged 400mm x 400mm squares. For ease of calculation, the target illuminance E0 of the upper, middle, and lower parts can be set to the same illuminance. For example, refer to... Figure 2 The illuminance at measurement point 301 on the upper part of blackboard 300 is E. 上 The illuminance at measurement point 302 in the middle of the blackboard is E. 中 The illuminance at measurement point 303 at the bottom of the blackboard is E. 下 That is, E 上 =E 中 =E 下 =E0.

[0034] S120. The target light distribution curve is obtained by inverse fitting based on the target parameters.

[0035] In some embodiments, the target parameters include the illuminance of the light source, the distance and height between the lens and the illuminated target, and the angle between at least one measurement point on the illuminated target and the light source. The target light distribution curve is obtained by inverse fitting based on the target parameters, including: obtaining a function of the target luminous intensity at each measurement point based on the distance and height between the lens and the illuminated target and the angle between at least one measurement point on the illuminated target and the light source; the curve of the function of the target luminous intensity at the measurement point in the coordinate system is the target light distribution curve.

[0036] As an example, three measurement points can be set on the blackboard 300: measurement point 301 (first measurement point) at the top of the blackboard 300, measurement point 302 (second measurement point) in the middle of the blackboard, and measurement point 303 (third measurement point) at the bottom of the blackboard. The distance between the lens 200 and the surface of the blackboard 300 is set to D, the distance between the lens 200 and the upper edge of the blackboard 300 is set to H, and the angle between the lens 200 and the first measurement point is set to γ1, the angle between the lens 200 and the second measurement point is set to γ2, and the angle between the lens 200 and the third measurement point is set to γ3.

[0037] Based on geometric relationships, the following can be calculated:

[0038]

[0039]

[0040]

[0041] Referring to the example in S110, the illuminance at the first, second, and third measurement points is the same, i.e., E 上 =E 中 =E 下=E0, then according to the relationship between illuminance, luminous intensity and luminous flux in geometric optics. The distribution function of the target light intensity (i.e., the target light distribution curve) is derived:

[0042]

[0043]

[0044]

[0045] Where, illuminance E is the luminous flux dφ projected onto the surface element containing the point divided by the area dA of that surface element, in lx. Luminous intensity I is the luminous flux dφ propagating from the light source within a solid angle element dΩ containing a given direction, divided by that solid angle element, in cd. Solid angle dΩ is the space enclosed by a closed cone of arbitrary shape. For a given vertex and direction, the corresponding solid angle is... Where r is the distance from the vertex to the center of dA.

[0046] S130. Based on the preset algorithm and the target light distribution curve, establish the correspondence between the light source beam angle and the target light distribution curve.

[0047] In some implementations, multiple sets of luminous intensity values ​​can be obtained using a preset interpolation algorithm, based on a function of the target luminous intensity at the measurement point. Then, a function of the light source beam angle is fitted using these multiple sets of luminous intensity values. Based on the function of the light source beam angle and the function of the target luminous intensity at the measurement point, the correspondence between the light source beam angle and the target light distribution curve is calculated.

[0048] As an example, refer to Figure 2 Similar to the examples in S110 and S120, assuming the light sources are symmetrically distributed, it is possible to obtain the light source by adjusting I. γ1 I γ2 I γ3 Interpolation calculations are performed to obtain multiple sets of light intensity values. These light intensity values ​​are then fitted with a function, allowing the light intensity distribution to be fitted as a function I with respect to the angle γ. (γ′i,c) That is, formulas 4, 5, and 6 mentioned above.

[0049] Then, refer to Figure 3 In the C-γ coordinate system, the light source is positioned at the origin, and its maximum intensity is I0. The light emitted by the light source follows a Braun distribution. That is, I... (γ,c) =I0*cosγ. Where C represents a set of planes that intersect the vertical line (polar axis) through the photon center. The angle γ represents the angle between the measurement direction and the common axis.

[0050] Due to the law of conservation of energy, the luminous flux emitted by an LED light source is equal to the luminous flux refracted through a lens. That is:

[0051] ∫∫I0*cosγ*dΩ=∫∫I (γ′,c) *dΩ′ (Formula 7)

[0052] Ω is the solid angle of the light emitted from the LED light source, Ω′ is the solid angle of the light refracted by the lens, γ is the angle between the light emitted from the light source in S120 and the optical axis (the z-axis is the optical axis in the C-γ spatial coordinate system), γ′ is the angle between the light refracted by the lens in S120 and the optical axis (z-axis), I γ′ The light intensity distribution function fitted in S120.

[0053] Solving the above function, we get:

[0054]

[0055] S140. The surface parameters of the lens are calculated based on the target light distribution curve and the correspondence between the light source beam angle and the target light distribution curve.

[0056] In some implementations, the coordinates of each point on the lens surface can be calculated based on Snell's law and the correspondence between the target light distribution curve, the light source beam angle, and the target light distribution curve.

[0057] As an example, refer to Figure 2 In the examples in S110 to S130, it is assumed that the surface parameters of the lens are composed of (y, z) coordinate points in the coordinate system.

[0058] According to Snell's Law:

[0059]

[0060] in, Let be the unit normal vector of the lens surface at a certain point. Let be the unit vector of the outgoing ray after refraction by the lens. Let n be the unit vector of the incident light rays emitted from the light source and incident on the curved surface of the lens, and let n be the refractive index.

[0061] Substituting the calculated formulas from the above steps into the equations, we can obtain the surface parameters of the lens:

[0062]

[0063] z(i+2)=tan(γ′ i+1 )*y(i+2) (Formula 11)

[0064] Finally, modeling software can be used to model and simulate the lens based on its surface parameters to test whether it meets the actual requirements.

[0065] The following embodiment of lens design, with reference to the above steps, further illustrates the method provided in this application.

[0066] In this embodiment, the standard blackboard is 1200mm*4000mm in size, with D=300mm, H=400mm, E0=500lx, and the starting coordinates of the lens surface are (0, 7). The target parameters are blackboard illuminance ≥500lx and uniformity U0≥0.80.

[0067] according to Where E i Let d be the illuminance value at a point on the blackboard surface. i For the corresponding illuminance at a certain point

[0068] The fitted target light distribution curve obtained by fitting is:

[0069] Positive y-axis direction: I γ′i =10I0*(cos(γ′) i )) 2 *sin(γ′ i )

[0070] Negative y-axis direction: I γ′i =10I0*(cos(γ′) i )) 10 *sin(γ′ i )

[0071] Then, an iterative algorithm is used to solve for the lens surface parameters using the target light distribution curve. For example, the fitted target light distribution curve can be substituted into Formula 8 to obtain a set of data γ′1, γ′2, γ′3, ..., γ′ i Next, based on formulas 9, 10, and 11, a series of solutions are obtained iteratively. y(i), z(i).

[0072] Figure 3 This is a cross-sectional schematic diagram of a blackboard lamp lens provided in an embodiment of this application. Figure 3 The surface parameters of the blackboard lamp lens shown are obtained using the method provided in this application.

[0073] As an example, refer to Figure 3 The cross-section of the blackboard lamp lens 200 includes: a first incident surface 205, a second incident surface 206, a third incident surface 207, a first transmission surface 201, a second transmission surface 202, a third transmission surface 203, and a total reflection surface 204.

[0074] The first end of the second transmission surface 202 extends into a first transmission surface 201, the second end of the second transmission surface 202 extends into a third transmission surface 203, the end of the third transmission surface 203 away from the second transmission surface 202 extends into a total reflection surface 204, the end of the total reflection surface 204 away from the third transmission surface 203 extends into a third incident surface 207, the end of the first transmission surface 201 away from the second transmission surface 202 extends into a first incident surface 205, and a second incident surface 206 is provided between the first incident surface 205 and the third incident surface 207.

[0075] In some embodiments, the cross-section of the first incident surface 205 includes a first curve, a second curve, and a third curve. The third curve is close to the first transmission surface, the first curve is close to the second incident surface, and the second curve is located between the first and third curves. The first curve has a radius of curvature of 2.63 mm and an arc length of 0.93 mm. The second curve has a radius of curvature of 3.26 mm and an arc length of 0.93 mm. The third curve has a radius of curvature of 4.25 mm and an arc length of 1.46 mm. The cross-section of the second incident surface 206 includes a first line segment, and the cross-section of the third incident surface 207 includes a second line segment. The angle between the first and second line segments is 80° to 85°, preferably 82°. The angle between the second line segment and the vertical direction is 0° to 3°, preferably 1°. The length of the second line segment is 1.6 mm to 1.8 mm, preferably 1.71 mm.

[0076] In some embodiments, the cross-sectional curves f1(y) of the first transmission surface 201 and the second transmission surface 202 are p1*y. 9 +p2*y 8 +p3*y 7 +p4*y 6 +p5*y 5 +p6*y 4 +p7*y 3 +p8*y 2 +p9*y+p 20 .

[0077] in:

[0078] -0.0002901≤p1≤-0.0001347, preferably -0.0002124;

[0079] 0.001381≤p2≤0.003473, preferably 0.002427;

[0080] -0.01257≤p3≤-0.003397, preferably -0.007986;

[0081] -0.008143≤p4≤-0.004044, preferably -0.00205;

[0082] 0.02369≤p5≤-0.07261, preferably 0.04815;

[0083] -0.08737≤p6≤-0.001327, preferably -0.04302;

[0084] -0.1118≤p7≤-0.008445, preferably -0.06011;

[0085] -0.1479≤p8≤-0.002051, preferably -0.07449;

[0086] 0.2642≤p9≤-0.3591, preferably 0.3117;

[0087] 6.967≤p 20 ≤-7.023. Preferred value is 6.995.

[0088] In some implementations, the cross-sectional curve of the total reflection surface 204 is f2(y) = p1*y 6 +p2*y 5 +p3*y 4 +p4*y 3 +p5*y 2 +p6*y 1 +p7.

[0089] in:

[0090] -0.08157≤p1≤0.01856, preferably -0.03151;

[0091] -1.857≤p2≤0.4575, preferably -0.6999;

[0092] -17.45≤p3≤4.64, preferably -6.407;

[0093] -86.72≤p4≤24.7, preferably -31.01;

[0094] -240≤p5≤73.01, preferably -83.49;

[0095] -351.6≤p6≤112.7, preferably -119.5;

[0096] -214.1≤p7≤70.07, preferably -72.

[0097] In some embodiments, the cross-section of the third transmission surface 203 includes a fourth curve, a fifth curve, a sixth curve, a seventh curve, an eighth curve, a ninth curve, and a tenth curve. The fourth curve is close to the total reflection surface, the tenth curve is close to the second transmission surface, and the fifth, sixth, seventh, eighth, and ninth curves are sequentially located between the fourth and tenth curves.

[0098] In some implementations, the radius of curvature of the fourth curve is 13.53 mm and the arc length is 0.39 mm. The radius of curvature of the fifth curve is 41.09 mm and the arc length is 0.58 mm. The radius of curvature of the sixth curve is 16.13 mm and the arc length is 0.70 mm. The radius of curvature of the seventh curve is 20.16 mm and the arc length is 0.67 mm. The radius of curvature of the eighth curve is 2.02 mm and the arc length is 0.31 mm. The radius of curvature of the ninth curve is 1.05 mm and the arc length is 0.45 mm. The radius of curvature of the tenth curve is 1.04 mm and the arc length is 0.27 mm.

[0099] In some embodiments, the light source may be arranged opposite to the first incident surface 205, the second incident surface 206, and the third incident surface 207. Light entering through the third incident surface 207 is reflected by the total internal reflection surface 204 and exits through the third transmission surface 203. Light entering through the second incident surface 206 exits through the second transmission surface 202. Light entering through the first incident surface 205 exits through the first transmission surface 201.

[0100] Figure 4 This is a schematic diagram of the structure of a lens surface parameter acquisition device provided in an embodiment of this application.

[0101] refer to Figure 4 The lens surface parameter acquisition device provided in this application includes:

[0102] The acquisition module 401 is used to acquire the target parameters when applying the lens.

[0103] The fitting module 402 is used to perform inverse fitting based on the target parameters to obtain the target light distribution curve.

[0104] The fitting module 402 is also used to establish the correspondence between the light source beam angle and the target light distribution curve based on the preset algorithm and the target light distribution curve.

[0105] The calculation module 403 is used to calculate the surface parameters of the lens based on the target light distribution curve, the correspondence between the light source beam angle and the target light distribution curve.

[0106] In some implementations, the target parameters include the light intensity of the light source, the distance and height between the lens and the illuminated target, and the angle between at least one measurement point on the illuminated target and the light source. The fitting module 402 is specifically used to inversely fit a function of the target luminous intensity at each measurement point based on the distance and height between the lens and the illuminated target, and the angle between at least one measurement point on the illuminated target and the light source. The curve of this function in the coordinate system is the target light distribution curve.

[0107] In some implementations, the fitting module 402 is specifically used to obtain multiple sets of luminous intensity values ​​based on a preset interpolation algorithm and a function of the target luminous intensity at the measurement point. Based on these multiple sets of luminous intensity values, a function of the light source beam angle is fitted. Based on the function of the light source beam angle and the function of the target luminous intensity at the measurement point, the correspondence between the light source beam angle and the target light distribution curve is calculated.

[0108] In some implementations, the calculation module 403 is used to calculate and obtain the coordinates of each point on the lens surface according to Snell's law and the correspondence between the target light distribution curve, the light source beam angle and the target light distribution curve.

[0109] In some embodiments, the device further includes a modeling module 404 for creating a model of the lens based on the lens's surface parameters.

[0110] This application also provides a blackboard lamp lens, the surface parameters of which are obtained according to the above-described method for obtaining lens surface parameters.

[0111] This application also provides a blackboard light, which includes the blackboard light lens described above.

[0112] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0113] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above descriptions are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for obtaining lens surface parameters, characterized in that, include: Obtain the target parameters when the lens is applied; The target light distribution curve is obtained by inverse fitting based on the target parameters; Based on the preset algorithm and the target light distribution curve, establish the correspondence between the light source beam angle and the target light distribution curve; The surface parameters of the lens are calculated based on the target light distribution curve and the correspondence between the light source beam angle and the target light distribution curve. The target parameters include the light intensity of the light source, the distance and height between the lens and the illuminated target, and the angle between at least one measurement point on the illuminated target and the light source; wherein, the target parameters also include blackboard illuminance and uniformity; the illuminated target includes measurement points in the vertical direction of the blackboard; The step of obtaining the target light distribution curve by inverse fitting based on the target parameters includes: Based on the distance and height between the lens and the illuminated target, and the angle between at least one measurement point on the illuminated target and the light source, a function of the target luminous intensity at each measurement point is obtained by inverse fitting. The curve of the function of the target luminous intensity at each measurement point in the coordinate system is the target light distribution curve.

2. The method according to claim 1, characterized in that, The step of establishing the correspondence between the light source beam angle and the target light distribution curve based on a preset algorithm and the target light distribution curve includes: Using a preset interpolation algorithm, multiple sets of luminous intensity values ​​are obtained based on a function of the target luminous intensity at the measurement point; Based on the multiple sets of luminous intensity values, a function of the light source beam angle is obtained by fitting. The correspondence between the light source beam angle and the target light distribution curve is calculated based on the function of the light source beam angle and the function of the target luminous intensity at the measurement point.

3. The method according to claim 2, characterized in that, The surface parameters of the lens are calculated based on the target light distribution curve, the correspondence between the light source beam angle and the target light distribution curve, including: According to Snell's law, the coordinates of each point on the lens surface are calculated based on the target light distribution curve, the correspondence between the light source beam angle and the target light distribution curve.

4. The method according to any one of claims 1-3, characterized in that, After obtaining the surface parameters of the lens, the process further includes: A model of the lens is established based on the surface parameters of the lens.

5. A lens surface parameter acquisition device, characterized in that, include: The acquisition module is used to acquire the target parameters when the lens is applied; The fitting module is used to perform inverse fitting based on the target parameters to obtain the target light distribution curve; The fitting module is also used to establish a correspondence between the light source beam angle and the target light distribution curve based on a preset algorithm and the target light distribution curve. The calculation module is used to calculate the surface parameters of the lens based on the target light distribution curve, the correspondence between the light source beam angle and the target light distribution curve; The target parameters include the light intensity of the light source, the distance and height between the lens and the illuminated target, and the angle between at least one measurement point on the illuminated target and the light source; wherein, the target parameters also include blackboard illuminance and uniformity; the illuminated target includes measurement points in the vertical direction of the blackboard; The fitting module is specifically used to inversely fit a function of the target luminous intensity at each measurement point based on the distance and height between the lens and the irradiated target and the angle between at least one measurement point on the irradiated target and the light source. The curve of the function of the target luminous intensity at the measurement point in the coordinate system is the target light distribution curve.

6. The apparatus according to claim 5, characterized in that, The fitting module is specifically used to obtain multiple sets of luminous intensity values ​​based on a function of the target luminous intensity at the measurement point using a preset interpolation algorithm. Based on the multiple sets of luminous intensity values, a function of the light source beam angle is obtained by fitting. The correspondence between the light source beam angle and the target light distribution curve is calculated based on the function of the light source beam angle and the function of the target luminous intensity at the measurement point.

7. The apparatus according to claim 6, characterized in that, The calculation module is used to calculate the coordinates of each point on the lens surface according to Snell's law and the correspondence between the target light distribution curve, the light source beam angle and the target light distribution curve.

8. The apparatus according to any one of claims 5-7, characterized in that, It also includes a modeling module for building a model of the lens based on the surface parameters of the lens.

9. A blackboard lamp lens, characterized in that, The surface parameters of the blackboard lamp lens are obtained by the lens surface parameter acquisition method provided according to any one of claims 1-4.

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