CN115654425A - Lens design method - Google Patents
Lens design method Download PDFInfo
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- CN115654425A CN115654425A CN202211446790.7A CN202211446790A CN115654425A CN 115654425 A CN115654425 A CN 115654425A CN 202211446790 A CN202211446790 A CN 202211446790A CN 115654425 A CN115654425 A CN 115654425A
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Abstract
The invention discloses a lens design method, which comprises the following steps: dividing an LED light source according to equal luminous flux to obtain a plurality of energy units; dividing the target surface according to the equal area to obtain sub-regions corresponding to the energy units one by one; and constructing a free-form surface lens according to the energy units and the corresponding sub-regions. By using the scheme of the invention, the LED light source can be assisted to generate uniform irradiance distribution on the target surface.
Description
Technical Field
The invention relates to the technical field of lenses, in particular to a lens design method.
Background
At present, LEDs are more and more widely used, and before high-power LED lighting components become lighting products, optical design is generally carried out twice. The primary optical design is mainly used for solving the problems of light-emitting angle, light intensity, luminous flux size, light intensity distribution, color temperature range and distribution and the like of the LED, and a general high-power LED is provided with a primary lens; the secondary optical design is to change the optical performance of the light passing through the primary lens through an optical lens so as to meet the requirements on large-area light projection and floodlight light distribution.
Disclosure of Invention
The invention provides a lens design method, which enables an LED light source to generate uniform irradiance distribution on a target surface by means of the lens.
Therefore, the invention provides the following technical scheme:
a lens design method, the method comprising:
dividing an LED light source according to equal luminous flux to obtain a plurality of energy units;
dividing the target surface according to the equal area to obtain sub-regions corresponding to the energy units one by one;
and constructing a free-form surface lens according to the energy units and the corresponding sub-regions.
Optionally, the dividing the LED light source by equal luminous flux to obtain a plurality of energy units includes:
the light energy spatial distribution of the LED light source is divided into a plurality of circular ring energy units with equal luminous flux;
the sub-regions corresponding to the energy units one by one are annular regions.
Optionally, the constructing a free-form surface lens according to the energy unit and the corresponding sub-region includes:
determining a lens bus according to the energy unit and the corresponding sub-area;
and rotating the lens bus for a circle around the symmetry axis to obtain the free-form surface lens.
Optionally, the determining a lens bus according to the energy unit and the corresponding sub-area includes:
determining all sampling points on a lens bus according to the energy units and the corresponding sub-areas;
and sequentially connecting the sampling points to obtain the lens bus.
Optionally, the determining all sampling points on the lens bus according to the energy unit and the corresponding sub-region includes:
constructing an iterative relationship between two adjacent sampling points on a free-form surface lens bus according to the energy unit and the corresponding sub-region;
and determining all sampling points on the lens bus according to the iterative relationship.
Optionally, the constructing an iterative relationship between two adjacent sampling points on the free-form surface lens bus according to the energy unit and the corresponding sub-region includes:
calculating two adjacent sampling points P according to the following formula i+1 （x i+1 ，y i+1 ) And P i （x i ，y i ) Coordinate iterative relationship between:
wherein the content of the first and second substances,
wherein, theta i Is a light ray OP i Angle of departure, theta i+1 Is a light ray OP i+1 Angle of departure, ray OP i Is the light source O (0, 0) to the sampling point P i （x i ，y i ) Of incident light, light OP i+1 From the center point O of the light source to the sampling point P i+1 （x i+1 ，y i+1 ) Of the incident light.
Optionally, the inner surface of the free-form surface lens is a spherical surface.
Optionally, the method further comprises:
determining a radius of the inner surface based on a center thickness of the free-form surface lens.
According to the lens design method provided by the embodiment of the invention, the LED light source is divided according to equal luminous flux to obtain a plurality of energy units; dividing the target surface according to the equal area to obtain sub-regions corresponding to the energy units one by one; and constructing a free-form surface lens according to the energy units and the corresponding sub-regions. The free-form surface lens constructed by the method can assist the LED light source to generate uniform irradiance distribution on a target surface, and meets application scenes with high requirements on irradiance distribution uniformity.
Drawings
FIG. 1 is a schematic diagram of a lens design according to an embodiment of the present invention;
FIG. 2 is a flow chart of a lens design method according to an embodiment of the invention;
FIG. 3 is a schematic diagram of the present invention for dividing the divided luminous fluxes and the target surface and their corresponding relationships;
FIG. 4 is a flow chart of the construction of a free-form lens according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of free-form surface tuning light distribution homogenization in an embodiment of the invention;
FIG. 6 is a schematic diagram illustrating calculation of sampling points on a lens bus according to an embodiment of the present invention;
FIG. 7 is a schematic view of a lens bus bar in an embodiment of the invention;
fig. 8 is a schematic diagram of a free-form lens obtained based on rotation of a generatrix of the lens shown in fig. 7 according to an embodiment of the present invention.
Detailed Description
In order to make the technical field to better understand the solution of the embodiments of the present invention, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings and the embodiments.
The lens is an optical element which is made of transparent substances (such as glass, crystal and the like) and has a part of spherical surface, can be widely applied to various fields such as security protection, vehicle-mounted, digital cameras, lasers, optical instruments and the like, and has increasingly wide application along with the continuous development of the market.
In some applications, it is desirable to have a uniform distribution of LED irradiance, such as in the backlight of a liquid crystal display. Because the LEDs are point light sources, the luminous intensity distribution of the LEDs is in rotational symmetry distribution, and the irradiance distribution on the target surface is also in rotational symmetry distribution. In order to improve the uniformity of LED irradiance distribution, the invention provides a lens design method, and designs a free-form surface lens, and the free-form surface lens is utilized to assist an LED light source to generate uniform irradiance distribution on a target surface.
The design principle of the lens for realizing uniform distribution of irradiance of the LED on the target surface is shown in figure 1, an LED light source is divided according to equal luminous flux, the target surface is divided according to equal area, and each luminous flux is controlled to be incident on the corresponding area, so that uniform irradiance distribution can be generated on the target surface.
Because the LED can be regarded as a point light source, the luminous intensity distribution of the LED is in rotational symmetry distribution, and the irradiance distribution on the target surface is also in rotational symmetry distribution, the structure of the free-form surface lens is also designed to be in a rotational symmetry structure. Therefore, only a lens bus needs to be designed, and the solid model of the lens can be obtained through bus rotation.
Fig. 2 is a flow chart of a lens design method according to an embodiment of the present invention, which includes the following steps:
And 203, constructing a free-form surface lens according to the energy units and the corresponding sub-areas.
In a specific application, the light energy spatial distribution of the LED light source can be divided into a plurality of circular ring energy units with equal luminous flux. Correspondingly, the sub-regions corresponding to the energy units one by one are annular regions.
As shown in fig. 3, a schematic diagram of the division of the light flux and the target surface and the correspondence thereof. The left graph is a schematic diagram of a plurality of circular ring energy units with equal luminous flux obtained by dividing the light energy spatial distribution of the LED light source, and the right graph is a schematic diagram of a plurality of circular ring sub-regions obtained by dividing the target surface according to the equal area, wherein the areas of the circular ring sub-regions are equal. Each circular ring energy unit corresponds to a circular ring sub-region, for example, a circular ring energy unit marked by oblique lines on the left corresponds to a circular ring sub-region marked by oblique lines on the right.
A process of constructing a free-form surface lens based on the divided energy units and the corresponding sub-regions is shown in fig. 4, and includes the following steps:
And 402, determining all sampling points on the lens bus according to the iterative relationship.
It should be noted that, when determining the iterative relationship, any group of energy units and corresponding sub-regions may be selected, which is not limited in this embodiment of the present invention.
The above process is explained in detail below.
Referring to fig. 3, a sub-region in a ring shape is taken from the right drawing, and as shown by hatching in the drawing, the area of the sub-region is:
the solid angles corresponding to the subregions are:
wherein Ω represents the solid angle corresponding to the sub-region, and r is the radius of the sub-region.
The solid angle refers to the angle of an object to the three-dimensional space of a specific point, and the space contained by a closed conical surface of an arbitrary shape is called a solid angle.
The cone angles formed between the shadow region and the inner and outer rings and directions are respectively theta i And theta i+1 The luminous flux in this sub-region is:
in the formula, I (θ) is the luminous intensity distribution of the LED light source, and the LED light source is in perfect lambertian distribution, that is:
total luminous flux phi of LED light source t Comprises the following steps:
the luminous flux of the LED light source is equally divided into N parts, and the luminous flux of each part (i.e., the energy unit described above) is:
in the formula, theta i Is a sampling light angle for equally dividing the luminous flux of the LED light source.
As shown in fig. 5. Knowing theta 0 =0, the sampling ray angle theta of the luminous flux of each LED light source can be calculated through an iterative relationship i I.e. the exit angle of the light ray OPi, the sampling angle of the exit light ray of the LED light source can be obtained.
Assuming that the radius of the target surface is R, the target surface is divided into N concentric circular sub-regions with equal area, as shown in the right diagram of fig. 4, the radius of each circular sub-region is R i (i =0,1,2, \8230;, N-1), wherein r 0 =0, the area of each subregion is S 0 ：
In this way, the radius r of each annular subregion is obtained i ：
Constructing an iterative relationship between two adjacent coordinate points on a generatrix of the free-form surface lens, and controlling each sampling light to enter a corresponding sampling point on a target surface, such as a light OP i Sub-zone T incident on the target surface i Sub-region T i Corresponding to a sampling radius r i The light OP is known from the edge ray principle i And a light ray OP i+1 All the light rays in between can be incident on the upper subregion T of the target surface i And sub-region T i+1 In this way, the equal luminous flux is controlled to be incident on the equal area, and the uniform irradiance distribution is realized on the target surface.
Therefore, the lens bus can be obtained by only calculating each sampling point on the lens bus, and the specific calculation process is as follows:
referring to FIG. 6, the position of the light source is taken as the origin of coordinates O (0, 0), the distance of the light source from the target surface is H, and the center point P of the outer surface of the lens is 0 Is h. The inner surface of the lens is spherical and does not affect the propagation direction of the light, so fig. 6 only shows the outer surface.
The lens center point P can be determined from the initial conditions 0 Coordinate (x) of 0 =0，y 0 = h), center point T of target surface 0 Coordinate (X) of 0 =0，Y 0 = H). Such that the vector OP of the first incident ray 0 Can be determined. Incident light OP 0 Through P 0 T incident on the target surface after point 0 Point such that the outgoing ray vector P 0 T 0 May also be obtained. From the vector form of the law of refraction, the following equation can be derived:
in the formula (I), the compound is shown in the specification,
are unit vectors and n represents the refractive index.
Thus, P can be calculated 0 Normal vector N of points 0 Thereby obtaining P 0 Tangent to the point. When the number of sampling points is large, it can be considered that P is exceeded 0 Tangent of point and second sampling lightIs handed over to P 1 （x 1 ，y 1 ) Point, so that the over P can be obtained 0 Tangent slope k of the point:
light OP 1 Corresponding exit angle θ 1 The method comprises the following steps:
from the above two formulae (10) and (11), P can be calculated 1 （x 1 ，y 1 ）。
Similarly, repeating the above process may result in the following iterative relationship:
from the above equations (12) and (13), the iterative relationship of coordinates between two adjacent sampling points can be calculated as follows:
and by utilizing the iterative relationship between two adjacent points, all sampling points on the generatrix of the free-form surface lens can be solved.
And 403, sequentially connecting the sampling points to obtain a lens bus.
And after all the sampling points on the free-form surface lens bus are obtained through calculation, connecting the sampling points to obtain the free-form surface lens bus.
And step 404, rotating the lens bus for a circle around the symmetry axis to obtain the free-form surface lens.
After all the sampling points on the generatrix of the free-form-surface lens are obtained through calculation, the generatrix of the free-form-surface lens can be obtained by connecting the sampling points, as shown in fig. 7.
Because the lens is in a rotational symmetry structure, the free-form surface lens can be obtained by rotating the lens bus around the symmetry axis for a circle.
It should be noted that, in the embodiment of the present invention, the inner surface of the free-form surface lens is a spherical surface, and the radius of the inner surface may be selected according to the central thickness of the lens. The central thickness refers to the central thickness of each micro lens forming the free-form surface lens, and the radius of a surface formed by splicing all the micro lenses is the radius of the inner surface.
For the point light source, the radius of the inner spherical surface does not affect the irradiance distribution on the target surface, a three-dimensional sphere is constructed by taking the origin as the center of the sphere, and the three-dimensional sphere and the lens model are subjected to Boolean difference to obtain the final free-form surface lens as shown in FIG. 8.
It should be noted that, in practical applications, the radius of the inner surface may be determined according to the central thickness of the free-form surface lens.
The free-form surface lens can be manufactured by selecting different materials according to application requirements, such as silica gel, optical-grade PMMA (polymethyl methacrylate and methyl methacrylate, commonly called acrylic), optical-grade Polycarbonate (PC for short), glass and the like. The free-form surface lens can be packaged on the LED by adopting a process matched with the used material, so that the light output by the LED is redistributed through the free-form surface lens to form uniformly distributed irradiance on a target surface.
According to the lens design method provided by the embodiment of the invention, the LED light source is divided according to equal luminous flux to obtain a plurality of energy units; dividing the target surface according to the equal area to obtain sub-areas corresponding to the energy units one by one; and constructing a free-form surface lens according to the energy units and the corresponding sub-regions. The free-form surface lens constructed by the method can assist the LED light source to generate uniform irradiance distribution on a target surface, and meets application scenes with high requirements on irradiance distribution uniformity.
While embodiments of the present invention have been described in detail, and while the invention has been described in detail with reference to specific embodiments thereof, the foregoing description of the embodiments is merely provided to facilitate the understanding of the methods and apparatus of the present invention and is intended to be a representative, rather than a full, embodiment of the invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort shall fall within the protection scope of the present invention, and the content of the present description shall not be construed as limiting the present invention. Therefore, any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A lens design method, the method comprising:
dividing an LED light source according to equal luminous flux to obtain a plurality of energy units;
dividing the target surface according to the equal area to obtain sub-areas corresponding to the energy units one by one;
and constructing a free-form surface lens according to the energy units and the corresponding sub-regions.
2. The method of claim 1, wherein dividing the LED light source into equal luminous flux to obtain a plurality of energy units comprises:
dividing the light energy spatial distribution of the LED light source into a plurality of circular ring energy units with equal luminous flux;
the sub-regions corresponding to the energy units one by one are annular regions.
3. The method of claim 2, wherein constructing a free-form lens from the energy cells and corresponding sub-regions comprises:
determining a lens bus according to the energy unit and the corresponding subarea;
and rotating the lens bus for a circle around the symmetry axis to obtain the free-form surface lens.
4. The method of claim 3, wherein determining a lens busbar from the energy cells and corresponding sub-regions comprises:
determining all sampling points on a lens bus according to the energy units and the corresponding sub-areas;
and sequentially connecting the sampling points to obtain the lens bus.
5. The method of claim 4, wherein determining all sample points on a lens bus from the energy cells and corresponding sub-regions comprises:
constructing an iterative relationship between two adjacent sampling points on a free-form surface lens bus according to the energy units and the corresponding sub-regions;
and determining all sampling points on the lens bus according to the iterative relationship.
6. The method of claim 5, wherein the constructing an iterative relationship between two adjacent sampling points on a generatrix of the free-form surface lens according to the energy unit and the corresponding sub-region comprises:
calculating two adjacent sampling points P according to the following formula i+1 （x i+1 ，y i+1 ) And P i （x i ，y i ) Coordinate iterative relationship between:
wherein the content of the first and second substances,
wherein, theta i Is a light ray OP i Angle of departure, theta i+1 Is a light ray OP i+1 Angle of departure, ray OP i Is the light source O (0, 0) to the sampling point P i （x i ，y i ) Of incident light, light OP i+1 From the center point O of the light source to the sampling point P i+1 （x i+1 ，y i+1 ) Of the incident light.
7. The method of any of claims 1 to 6, wherein the inner surface of the free-form lens is spherical.
8. The method of claim 7, further comprising:
determining a radius of the inner surface based on a center thickness of the free-form surface lens.
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| CN201902993U (en) * | 2010-12-02 | 2011-07-20 | 西安中科麦特电子技术设备有限公司 | Novel LED illuminating optical lens |
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| CN104879711A (en) * | 2015-06-02 | 2015-09-02 | 江南大学 | Design method of double-free-form-surface LED (light emitting diode) uniform-light lens based on cubic spline |
| CN108870096A (en) * | 2017-05-16 | 2018-11-23 | 中国科学院工程热物理研究所 | Lamps and lanterns based on quantum measurement optical mirror |
| CN113777782A (en) * | 2021-09-13 | 2021-12-10 | 南通大学 | LED free-form surface lens design method based on bidirectional feedback grid method |
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- 2022-11-18 CN CN202211446790.7A patent/CN115654425B/en active Active
Patent Citations (5)
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|---|---|---|---|---|
| CN201902993U (en) * | 2010-12-02 | 2011-07-20 | 西安中科麦特电子技术设备有限公司 | Novel LED illuminating optical lens |
| CN102486290A (en) * | 2010-12-02 | 2012-06-06 | 西安大昱光电科技有限公司 | Light-emitting diode (LED) indoor illumination optical lens |
| CN104879711A (en) * | 2015-06-02 | 2015-09-02 | 江南大学 | Design method of double-free-form-surface LED (light emitting diode) uniform-light lens based on cubic spline |
| CN108870096A (en) * | 2017-05-16 | 2018-11-23 | 中国科学院工程热物理研究所 | Lamps and lanterns based on quantum measurement optical mirror |
| CN113777782A (en) * | 2021-09-13 | 2021-12-10 | 南通大学 | LED free-form surface lens design method based on bidirectional feedback grid method |
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