CN109445093A - A kind of LED free-form surface lens array apparatus for inclined surface Uniform Illumination - Google Patents

Abstract

The invention discloses an LED free-form surface lens array device used for uniform illumination of inclined surfaces, belonging to the technical field of non-imaging optics and laser beam shaping. It includes a number of free-form surface lens units (U) and LED light source units (V) evenly arranged in rows and columns; each free-form surface lens unit (U) has the same shape, and each LED light source unit (V) is also the same, free The number of curved lens units (U) and LED light source units (V) are the same and correspond one-to-one; the optical axes of each LED light source unit and the corresponding free-form curved lens unit are coincident, and the light emitted from the LED light source unit passes through the corresponding free-form curved lens. After the unit is deflected, a predetermined uniform light distribution is generated on the inclined illumination surface, and the free-form surface lens unit can be realized by injection molding technology with materials such as optical resin. The invention has compact and simple structure, good shaping effect, high energy utilization rate, strong practicability and wide application range.

Description

A LED free-form surface lens array device for uniform illumination of inclined surfaces

technical field

The invention relates to the technical field of non-imaging optics and lighting, in particular to an LED free-form surface lens array device used for uniform illumination of inclined surfaces.

Background technique

Different from traditional coaxial lighting, oblique lighting removes the coaxial limitation and greatly improves the flexibility of lighting. It has a wide range of applications in practice, such as urban road lighting, tunnel lighting, and urban landscape lighting. In order to improve the light intensity, an actual oblique lighting system is generally constituted by an array of a group of beam shaping lens units. Since each beam-shaping lens unit is identical, the key to designing an oblique illumination system is to design a single beam-shaping lens unit. The beam shaping lens unit redistributes the light emitted from the light source by means of a certain optical curved surface. Compared with traditional optical surfaces, freeform surfaces have a very high degree of design freedom, which can greatly improve the ability and flexibility of manipulating light. The use of free-form surfaces for beam regulation can obtain an optical system with a compact structure and excellent performance, and more importantly, a new oblique lighting system that cannot be achieved by traditional optical surfaces can be realized. The extremely free and flexible surface structure of free-form surfaces not only brings us opportunities, but also brings great design challenges. The key point and difficulty of free-form surface lighting is how to control the light according to the requirements (given the distribution of incident light and the distribution of outgoing light). ) to inverse the free-form surface shape.

Among the existing beam shaping methods for free-form surfaces, the Raymapping method proposed in Chinese Patent No. 200910046129.5 predefines the mapping relationship between incident rays and outgoing rays according to energy conservation, and then obtains the surface shape by numerical solution. In the Ray mapping method, the integrability of the mapping relationship determines the continuity of the surface. Since it is difficult to obtain a mapping relationship that satisfies the integrable condition in free-form surface beam shaping, the free-form surface is discontinuous or the actual light distribution and target light There is a big difference between the distributions. The MA (Monge-Ampère, MA) method proposed in Chinese patent 201210408729.3 converts a single free-form surface shaping problem into an MA equation according to the law of energy conservation and refraction, and obtains the numerical solution of the beam shaping problem by numerically solving the MA equation. Compared with the Ray mapping method, the MA method can obtain continuous free-form surfaces, and the actual light distribution is in good agreement with the target light distribution. The Supporting quadric method discretizes a continuous light distribution, and uses many quadric surfaces (such as paraboloids, ellipsoids, etc.) to construct free-form surfaces, so as to obtain an approximate solution to the beam shaping problem. The above methods have been widely studied in beam shaping of coaxial free-form surfaces, but they cannot solve the problem of non-coaxial oblique illumination. Using a coaxially designed lighting system for inclined surface lighting will inevitably cause the actual light distribution on the inclined surface to significantly deviate from the predetermined light distribution, which cannot meet the actual inclined lighting requirements; it cannot achieve effective energy distribution, which will inevitably lead to energy waste.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a free-form surface lens array device for uniform illumination of inclined surfaces.

The LED free-form surface lens array device for uniform illumination of inclined surfaces includes a number of free-form surface lens units (U) and LED light source units (V) uniformly arranged in rows and columns; each free-form surface lens unit (U) The shape is the same, and each LED light source unit (V) is also the same, the number of free-form lens units (U) and LED light source units (V) are the same, and correspond one-to-one; each LED light source unit and the corresponding free-form surface lens unit The optical axis of the LED light source unit coincides, and the light emitted from the LED light source unit is deflected by the corresponding free-form surface lens unit to produce a predetermined uniform light distribution on the inclined illumination surface; the specific design steps of the free-form surface lens unit are as follows:

(1) The optical path structure of the free-form surface lens is set, and the light source enters the free-form surface lens through the incident surface of the free-form surface lens; it is emitted from the exit surface of the free-form surface lens, and a predetermined uniform light distribution is generated on the inclined illumination surface; The surface is a free-form surface; the free-form surface lens is designed according to the initial design parameters;

(2) The global rectangular coordinate system xyz is established with the light source S as the coordinate origin, and the position of the point P on the free-form surface of the free-form surface lens determined in step (1) is expressed in spherical coordinates as Taking the intersection point B ₃ of the oblique illumination surface and the z-axis as the coordinate origin, establish a local coordinate system x ₁ y ₁ z ₁ on the oblique illumination surface, and make the x axis of the global coordinate system xyz and the local coordinate system x ₁ y ₁ z ₁ The direction of the x ₁ axis is the same; the angle between the z ₁ axis of the local coordinate system x ₁ y ₁ z ₁ and the z axis of the global coordinate system xyz is β, β≠0°; when from the z axis of the global coordinate system xyz to the local When the z ₁ axis of the coordinate system x ₁ y ₁ z ₁ rotates counterclockwise, β<0; when the z 1 axis from the z axis of the global coordinate system xyz to the z ₁ axis of the local coordinate system x ₁ y ₁ z ₁ is clockwise When rotating, β>0; the coordinates of the landing point T of the outgoing light on the oblique illumination surface in the global coordinate system xyz are expressed as (t _x , t _y , t _z ), and in the local coordinate system x ₁ y ₁ z ₁ The coordinates of t are expressed as (t _x1 , t _y1 , t _z1 ); the vector P is the position vector of point P, which is a vector pointing to the point P from the origin of the global Cartesian coordinate system; the vector T is the position vector of point T, which is a The vector pointing from the origin of the global Cartesian coordinate system to the point T; according to the law of refraction O=n×I+P ₁ ×N, the unit direction vector O=(O _x , O _y , O _z ) of the emitted light can be obtained, and established Coordinate relationship between point P and target point T

Among them, P _x , P _y and P _z are the three components of the position vector P of the point P; O _x , O _y and O _z are the three components of the unit direction vector O of the outgoing ray at the point P; N is the free-form surface at the point unit normal vector at P, The angle α is the angle between the vector I and the vector N; n is the refractive index of the material used for the free-form surface lens;

(3) The coordinate relationship between the point P and the target point T obtained according to step (2) also needs to satisfy the equation of the inclined illumination surface in the global coordinate system:

At _x +Ct _z +D=0

Among them, A=sinβ, C=cosβ and D=-C×L, L is the z-coordinate of the intersection point _B3 of the z-axis of the oblique illumination surface and the global coordinate system xyz; the global coordinate of the target point T is further obtained according to this equation

(4) According to the coordinate relationship between the point P and the target point T obtained in step (2), there are the following coordinate transformation relationships

where J(T) is the Jacobi matrix of the position vector T,

(5) According to the law of local energy conservation, without considering the energy loss, it is required that any light beam emitted by the light source is deflected by the free-form surface lens and all its energy is transmitted to the target illumination area on the inclined illumination surface, that is, The deflection of the beamlet by the free-form surface lens satisfies the following energy relation

in, is the intensity distribution of the light source, E(t _x1 , t _y1 ) is the illuminance distribution of the target illumination area on the oblique illumination surface, J(T) is the Jacobi matrix of the position vector T, 0≤θ≤2π, in is the maximum divergence angle of the light beam incident on the free-form surface lens;

(6) While the free-form surface satisfies the energy transfer equation in step (5), it must also ensure that the boundary rays of the light beam are deflected by the free-form surface and enter the boundary of the illumination area of the target surface, that is, the following boundary conditions are satisfied

Among them, Ω ₁ represents the total solid angle of the light beam incident on the free-form surface lens, Ω ₂ represents the target illumination area on the oblique illumination surface, and are the boundaries of regions Ω ₁ and Ω ₂ , respectively;

(7) Simultaneously solve the energy transfer equation in step (5) and the boundary conditions in step (6) to obtain a set of discrete data points, which can be used for inclined surfaces by surface fitting of the set of data points. The freeform surface profile of the freeform lens for illumination.

Preferably, the incident surface ( S1 ) of the free-form curved lens is a spherical surface, and each LED light source unit is located at the spherical center of the incident surface of the corresponding free-form curved lens.

Preferably, the refractive index of each area of the free-form surface lens is the same; the surrounding medium of the free-form surface lens is air.

Preferably, the free-form surface lens is a shaping lens after the light source, that is, a secondary lens.

Compared with the prior art, the present invention has the following beneficial effects:

1) The free-form surface lens array device for uniform illumination of inclined surfaces proposed by the present invention can achieve predetermined uniform light distribution on the inclined illumination surfaces;

2) The free-form surface lens array device for the uniform illumination of the inclined surface proposed by the present invention can realize the effective regulation of the LED outgoing beam and obtain a higher energy utilization rate;

3) The free-form surface lens array device for uniform illumination of inclined surfaces proposed by the present invention can promote the application of free-form surfaces in semiconductor lighting;

4) The free-form surface lens array device for uniform illumination of inclined surfaces proposed by the present invention is helpful to form a high-efficiency and energy-saving semiconductor lighting technology.

Description of drawings

1 is a schematic structural diagram of a free-form surface lens array device for uniform illumination of inclined surfaces;

Fig. 2 is the design principle diagram of the free-form surface lens unit;

Fig. 3 is the optical structure of free-form surface lens unit;

4 is a free-form surface lens unit as a secondary lens for LED beam shaping;

Fig. 5 is the model of the free-form surface lens unit in the embodiment;

Fig. 6 is the illumination spot of the free-form surface lens unit on the inclined illumination surface in the embodiment;

7 is a model of a free-form surface lens array device in an embodiment;

FIG. 8 is an illumination light spot on an oblique illumination surface of the free-form surface lens array device in the embodiment.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described below with reference to the accompanying drawings.

The LED free-form surface lens array device for uniform illumination of inclined surfaces includes an LED free-form surface lens array composed of free-form surface lens units U uniformly arranged in rows and columns, see Figure 1; each free-form surface lens unit has the same shape , and each LED light source unit (V) is also the same, the number of free-form surface lens units (U) and LED light source units (V) are the same, and correspond one-to-one; the light emitted by the LED light source is deflected by the corresponding free-form surface lens unit. A predetermined uniform light distribution is generated on the inclined illumination surface; the specific design steps of the free-form surface lens unit are as follows:

(1) Setting the optical path structure of the free-form surface lens, the incident surface of the free-form surface lens adopts a spherical surface, the exit surface is a free-form surface, and the light source is located at the spherical center of the incident surface; the light source is refracted by the free-form surface lens and obtains the target on the inclined illumination surface Illuminance distribution; free-form surface design according to initial design parameters;

(2) The global rectangular coordinate system xyz is established with the light source S as the coordinate origin, and the position of the point P on the free-form surface of the free-form surface lens determined in step (1) is expressed in spherical coordinates as Taking the intersection point B ₃ of the oblique illumination surface and the z-axis as the coordinate origin, establish a local coordinate system x ₁ y ₁ z ₁ on the oblique illumination surface, and make the x axis of the global coordinate system xyz and the local coordinate system x ₁ y ₁ z ₁ The direction of the x ₁ axis is the same; the angle between the z ₁ axis of the local coordinate system x ₁ y ₁ z ₁ and the z axis of the global coordinate system xyz is β; when from the z axis of the global coordinate system xyz to the local coordinate system x ₁ y When the z ₁ axis of ₁ z ₁ rotates counterclockwise, β<0; when the z 1 axis from the z axis of the global coordinate system xyz to the z ₁ axis of the local coordinate system x ₁ y ₁ z ₁ rotates clockwise, β> 0. The coordinates of the landing point T of the outgoing light on the oblique illumination surface in the global coordinate system xyz are expressed as (t _x , t _y , t _z ), and the coordinates under the local coordinate system x ₁ y ₁ z ₁ are expressed as (t _x1 ,t _y1 ,t _z1 ). The vector P is the position vector of the point P, which is a vector pointing to the point P from the origin of the global coordinate system; the vector T is the position vector of the point T, which is a vector pointing to the point T from the origin of the global coordinate system; see Figure 2 , according to the law of refraction O=n×I+P ₁ ×N, obtain the unit direction vector O=(O _x , O _y , O _z ) of the emitted light, and establish the coordinate relationship between the point P and the target point T

Among them, P _x , P _y and P _z are the three components of the position vector P of the point P; O _x , O _y and O _z are the three components of the unit direction vector O of the outgoing ray at the point P; N is the free-form surface at the point Unit French at P, The angle α is the angle between the vector I and the vector N; n is the refractive index of the material used for the free-form lens, and the medium around the free-form lens is air;

(3) The coordinate relationship between the point P and the target point T obtained according to step (2) also needs to satisfy the equation of the inclined illumination surface in the global coordinate system, and the following relationship

At _x +Ct _z +D=0

Among them, A=sinβ, C=cosβ and D=-C×L, L is the z-coordinate of the intersection point _B3 of the z-axis of the oblique illumination surface and the global coordinate system xyz; further obtain the global coordinate of the target point T according to this relationship

(4) According to step (3), the global coordinates (t _x , t _y , t _z ) of the point P are obtained, and the local coordinates (t _x1 , t z ) of the point P are obtained from the transformation relationship between the global coordinates and the local coordinates of the point P t _y1 ,t _z1 ), there is the following relation

(5) According to the law of local energy conservation, without considering the energy loss, it is required that any light beam emitted by the light source is deflected by the free-form surface lens and all its energy is transmitted to the target illumination area on the inclined illumination surface, that is, The deflection of the beamlet by the free-form surface lens satisfies the following energy relation

in, is the intensity distribution of the light source, E(t _x1 , t _y1 ) is the illuminance distribution of the target illumination area on the oblique illumination surface, J(T) is the Jacobi matrix of the position vector T, 0≤θ≤2π, in is the maximum divergence angle of the light beam incident on the free-form surface lens unit;

(6) While the free-form surface satisfies the energy transfer equation in step (5), it must also ensure that the boundary rays of the light beam are deflected by the free-form surface and enter the boundary of the illumination area of the target surface, that is, the following boundary conditions are satisfied

Among them, Ω ₁ represents the total solid angle of the light beam incident on the free-form surface lens, Ω ₂ represents the target illumination area on the oblique illumination surface, and are the boundaries of regions Ω ₁ and Ω ₂ , respectively;

(7) Simultaneously solve the energy transfer equation in step (5) and the boundary conditions in step (6) to obtain a set of discrete data points, and a free-form surface element can be obtained by performing surface fitting on the set of data points.

The incident surface S1 of the free-form curved lens unit is a spherical surface, and the exit surface S2 is a free-form curved surface, see FIG. 3 . The free-form surface lens unit is a shaping lens after the LED light source, that is, the LED secondary lens, see FIG. 4 .

Example: The free-form surface lens unit intends to adopt the structure type shown in Figure 3, the incident surface S1 adopts a spherical surface, the exit surface S2 is a free-form surface, the LED light source is located at the center of the sphere of the incident surface S1, and it is assumed that the intensity of the LED light source distribution satisfies It is required that the outgoing beam of the light source is deflected by the free-form surface lens to generate a uniform rectangular illumination spot in the target illumination area of the inclined illumination surface. The z-coordinate of the vertex of the spherical surface S1 of the incident surface is 12mm, the z-coordinate of the vertex of the free-form surface S2 of the output surface is 25mm, the z-coordinate of the intersection point _B3 of the oblique illumination surface and the z-axis of the global coordinate system xyz is 3000mm, and the z-coordinate of the oblique illumination surface is 3000mm. The angle of inclination is β=34°; the length of the rectangular illumination spot is 4000mm, the width is 5000mm, the refractive index of the free-form surface lens is n=1.4935, the medium around the lens is air, and the maximum outgoing angle of the light source incident on the free-form surface lens is

According to the law of refraction O=n×I+P ₁ ×N, the unit direction vector O=(O _x , O _y , O _z ) of the emitted light is obtained, and the coordinate relationship between the point P and the target point T is established

Among them, P _x , P _y and P _z are the three components of the position vector P of the point P; O _x , O _y and O _z are the three components of the unit direction vector O of the outgoing ray at the point P; N is the free-form surface at the point Unit French at P, The angle α is the angle between the vector I and the vector N. The coordinate relationship between the point P and the target point T also needs to satisfy the equation of the inclined illumination surface in the global coordinate system, which has the following relationship

At _x +Ct _z +D=0

Among them, A=sinβ, C=cosβ and D=-C×L, L is the z-coordinate of the intersection point _B3 of the z-axis of the oblique illumination surface and the global coordinate system xyz; further obtain the global coordinate of the target point T according to this relationship

From the global coordinates (t _x , _ty , t _z ) of the point P, and the transformation relationship between the global coordinates and the local coordinates of the point P, the local coordinates (t _x1 , t _y1 , t _z1 ) of the point P are obtained, there are The following relation

According to the law of local energy conservation, without considering the energy loss, it is required that any light beam emitted by the light source is deflected by the free-form surface lens and all its energy is transmitted to the target illumination area on the inclined illumination surface, that is, the free-form surface lens. The deflection of the beamlet satisfies the following energy relation

in, is the intensity distribution of the light source, E(t _x1 , t _y1 ) is the illuminance distribution of the target illumination area on the oblique illumination surface, J(T) is the Jacobi matrix of the position vector T, 0≤θ≤2π, in is the maximum divergence angle of the light beam incident on the free-form surface lens. Further simplifying the energy transfer equation, the following elliptical Monge-Ampère equation can be obtained

Among them, ρ _θθ , and are ρ with respect to the angle θ and The second partial and mixed partial derivatives of , the coefficients In order to ensure the shape of the target illumination area on the oblique illumination surface, certain boundary conditions need to be applied.

in and area respectively and border.

For such a highly nonlinear partial differential equation, only its numerical solution can be obtained. First, it is necessary to discretize the region Ω ₁ where the light beam incident on the free-form surface lens is located to obtain a set of discrete grid points, and each grid node corresponds to a partial differential equation; then, the difference is used to replace the partial differential equation in The energy transfer equation and boundary conditions can be converted into a nonlinear equation system; finally, a set of discrete data points can be obtained by solving the nonlinear equation system using Newton's method. A free-form surface can be obtained by performing surface fitting on the set of discrete data points in CAD software, so that the free-form surface lens model can be constructed, as shown in FIG. 5 . Trace the light rays on the free-form surface lens model, and obtain the illuminance distribution diagram on the inclined target illumination surface, as shown in Figure 6. Subsequently, the free-form surface lens units are arranged along the x-axis and y-axis of the global coordinate system xyz into a 3×3 free-form surface lens array, and the array spacing of the free-form surface lens units in the x-axis and y-axis directions is both 50mm. See Figure 7. Trace the light rays on the free-form surface lens array model, and obtain the illuminance distribution diagram on the inclined target illumination surface, as shown in Figure 8. The illuminance distribution diagram clearly shows that the free-form surface lens array proposed by the present invention for uniform illumination of inclined surfaces effectively achieves the predetermined target illumination.

It can be seen from the examples that the use of the free-form surface lens array for uniform illumination of the inclined surface proposed by the present invention can realize a predetermined light distribution on the inclined illumination surface, obtain a continuous free-form surface, realize the machinability of the free-form surface, and have the advantages of significant practical significance.

Claims (4)

1. An LED free-form surface lens array device for inclined plane uniform illumination is characterized by comprising a plurality of free-form surface lens units (U) and LED light source units (V), wherein the free-form surface lens units (U) and the LED light source units (V) are uniformly distributed in rows and columns; each free-form surface lens unit (U) is the same in shape, each LED light source unit (V) is the same, and the free-form surface lens units (U) and the LED light source units (V) are the same in number and are in one-to-one correspondence; the optical axis of each LED light source unit is superposed with the optical axis of the corresponding free-form surface lens unit, and the emergent light of the LED light source unit is deflected by the corresponding free-form surface lens unit to generate preset uniform light distribution on the inclined lighting surface; the specific design steps of the free-form surface lens unit are as follows:

(1) setting a light path structure of the free-form surface lens, wherein a light source enters the free-form surface lens through an incident surface of the free-form surface lens; emitting the light from the emergent surface of the free-form surface lens, and generating a predetermined uniform light distribution on the inclined illumination surface; the emergent surface is a free-form surface; carrying out free-form surface design on the free-form surface lens according to the initial design parameters;

(2) establishing a global rectangular coordinate system xyz by taking the light source S as the origin of coordinates, and expressing the position of the point P on the free-form surface of the free-form surface lens determined in the step (1) by using a spherical coordinate asAt the intersection B of the oblique illumination plane and the z-axis₃For the origin of coordinates, a local coordinate system x is established on the inclined illumination surface₁y₁z₁And the x-axis of the global coordinate system xyz and the local coordinate system x are set₁y₁z₁X of₁The axial directions are the same; local coordinate system x₁y₁z₁Z of (a)₁The included angle between the axis and the z-axis of the global coordinate system xyz is β ≠ 0 DEG, when the z-axis of the global coordinate system xyz is converted into the local coordinate system x₁y₁z₁Z of (a)₁β when the shaft is rotating in a counterclockwise direction<0; when going from the z-axis of the global coordinate system xyz to the local coordinate system x₁y₁z₁Z of (a)₁β when the shaft is rotating in the clockwise direction>0; the coordinate of the falling point T of the emergent ray on the inclined illumination surface in the global coordinate system xyz is expressed as (T)_x,t_y,t_z) In a local coordinate system x₁y₁z₁The coordinates of the lower part are represented by (t)_x1,t_y1,t_z1) (ii) a The vector P is a position vector of the point P and is a vector pointing to the point P from the origin of the global rectangular coordinate system; the vector T is a position vector of the point T and is a vector pointing to the point T from an origin of the global rectangular coordinate system; according to the law of refraction O-nxI + P₁X N, and obtaining the unit direction vector O ═ O (O) of the emergent ray_x,O_y,O_z) And establish points P andcoordinate relationship between target points T

Wherein, P_x、P_yAnd P_zThree components of a point P position vector P; o is_x、O_yAnd O_zThree components of the unit direction vector O of the emergent ray at the point P; n is the unit normal vector of the free form surface at point P,the angle α is the angle between vector I and vector N, N is the refractive index of the material used for the free-form surface lens;

(3) and (3) according to the coordinate relation between the point P and the target point T obtained in the step (2), the equation of the inclined illumination surface in the global coordinate system is also required to be satisfied:

At_x+Ct_z+D＝0

where a is sin β, C is cos β, and D is cxl, and L is a z-axis intersection B of the oblique illumination plane and the global coordinate system xyz₃Z-coordinate of (a); further obtaining the global coordinate of the target point T according to the equation

(4) According to the coordinate relationship between the point P and the target point T obtained in the step (2), the following coordinate transformation relationship exists

Wherein J (T) is a Jacobi matrix of the position vector T,

(5) according to the local energy conservation law, under the condition of not considering energy loss, any beamlet emitted by a light source is required to transmit all energy of the beamlet to a target illumination area on an inclined illumination surface after being deflected by a free-form surface lens, namely the deflection of the beamlet by the free-form surface lens meets the following energy relation expression

Wherein,as the intensity distribution of the light source, E (t)_x1,t_y1) J (T) is a Jacobi matrix of position vectors T,0≤θ≤2π，whereinIs the maximum divergence angle of the light beam incident to the free-form surface lens;

(6) the free-form surface meets the energy transmission equation in the step (5), and simultaneously ensures that the boundary light of the light beam is deflected by the free-form surface and then enters the boundary of the illumination area of the target surface, namely the following boundary conditions are met

Wherein omega₁Representing the total solid angle, omega, of the beam incident on the free-form lens₂Representing the illuminated area of the object on the inclined illumination plane,andare respectively region omega₁And Ω₂The boundary of (2);

(7) and (4) solving the energy transmission equation in the step (5) and the boundary condition in the step (6) simultaneously to obtain a group of discrete data points, and performing surface fitting on the group of data points to obtain the free-form surface type of the free-form surface lens for the inclined surface illumination.

2. The LED free-form surface lens array device for tilted surface uniform illumination as claimed in claim 1, wherein the incident surface (S1) of the free-form surface lens is a spherical surface, and each LED light source unit is located at the spherical center of the incident surface of its corresponding free-form surface lens.

3. The LED free-form surface lens array device for the inclined plane uniform illumination as claimed in claim 1, wherein the refractive index of each region of the free-form surface lens is the same; the surrounding medium of the free-form surface lens is air.

4. The LED free-form surface lens array device for the inclined plane uniform illumination as claimed in claim 1, wherein the free-form surface lens is a shaping lens behind a light source, namely a secondary lens.