CN103912809B - Zigzag type LED illumination optical system - Google Patents

Abstract

The present invention relates to the collimating optical system technical field of LED illumination, be specifically related to a kind of Zigzag type LED illumination optical system, comprise free-form surface lens and free-form surface reflector, described free-form surface lens and free-form surface reflector coaxial, spacing is 0.01m-0.1m; Described free-form surface lens comprises first surface, is Rotational Symmetry free form surface; Second curved surface is Rotational Symmetry free form surface; 3rd curved surface, for rotating parabola, paraboloidal focus is the virtual optical source point of the second curved refractive light; 5th curved surface is Rotational Symmetry free form surface; And the 4th curved surface, be the face of cylinder, for connecting the 3rd curved surface and the 5th curved surface; Described free-form surface reflector, is made up of three curved surfaces.Present invention achieves the illumination of any angle of visual field, and the light efficiency of optical system can not be reduced because of total reflection.

Description

Zigzag type LED illumination optical system

Technical field

The present invention relates to the collimating optical system technical field of LED illumination, be specifically related to a kind of Zigzag type LED illumination optical system.

Technical background

LED is as a kind of new type light source, and due to its specular removal, the advantages such as the life-span is long, nonhazardous make it the perfect replacer becoming traditional light source such as incandescent lamp, fluorescent lamp.But the light distribution due to LED is circular lambert's type distribution, if directly apply to illumination, then can form very uneven Illumination Distribution in target face, cannot meet various illumination occasion to the requirement of light fixture optical property.In order to make LED better be applied to lighting field, need designs secondary optics system to redistribute the light distribution of LED, it can be formed evenly or other specific Illumination Distribution in target face.

In order to realize the set Illumination Distribution of LED lamp in target face, the design LED free-form surface lens that adopts reaches this object more at present.A kind of lens controlling LED light bundle are disclosed in Chinese invention patent description CN101144863B.These lens utilize free form surface beam projecting face accurately to control the distribution of outgoing beam energy space, can realize the light spot shape and the Illumination Distribution that meet different illumination needs.A kind of Narrow-beam LED lamp optical system is disclosed in Chinese utility model patent description CN20320202741U.This optical system utilizes Fresnel Lenses to assemble low-angle light; At employing fully reflecting surface, set illumination is realized to the light of wide-angle.Thus achieve the low-angle specular removal illumination of LED.Except lens, the optical system of reflection-type is also used in the middle of LED illumination.A kind of free-form surface LED optical system based on high diffuse reflectance is proposed in Chinese invention patent application description CN103234173A.This optical system utilizes free form surface reflecting surface to realize redistributing LED light line.

Although LED secondary lens can the set illumination in realize target face, but also there is following problem: (1) is owing to existing total reflection phenomenon when light is propagated from optically denser medium to optically thinner medium, therefore, when illumination field of view angle is about greater than 60 degree, the existence due to total reflection phenomenon makes the light efficiency of lens constantly decline along with the increase of the angle of visual field; (2) according to the definition of brightness, the less brightness of size of light source is higher, and now people just feels more " dazzling ".Because the luminous size of LED is minimum, be generally 1mm × 1mm, therefore there is more serious " dazzling " phenomenon in the LED optical system of transmission-type.Compare LED secondary lens, the reflective LED secondary optical system angle of visual field is unrestricted, there is no " dazzling " phenomenon, but in actual use, the devices such as LED chip, fin, pcb board are installed due to needs, therefore there is occlusion issue, can cause the light that can not all utilize LED to send or some light can not through the shaping direct irradiation of optical system to target face.

Summary of the invention

The object of the invention is for general illumination occasions such as room lightings, design the LED secondary optical system of the Zigzag type of a kind of realize target region Uniform Illumination, there is not " dazzling " phenomenon in this optical system, have higher light efficiency simultaneously.

For achieving the above object, the Zigzag type LED illumination optical system designed by the present invention, comprises free-form surface lens and free-form surface reflector, described free-form surface lens and free-form surface reflector coaxial, spacing is 0.01m-0.1m;

Described free-form surface lens comprises first surface, is Rotational Symmetry free form surface, for the light refraction sent by LED, makes the light ray parallel after refraction in z-axis; Second curved surface is Rotational Symmetry free form surface, for the light refraction sent by LED, makes the light after refraction become the light sent with spot light in x-axis and overlaps; 3rd curved surface, for rotating parabola, paraboloidal focus is the virtual optical source point of the second curved refractive light, by the light reflection after the second curved refractive to the direction parallel with z-axis; 5th curved surface, for Rotational Symmetry free form surface, for controlling the light being parallel to z-axis after first surface, the second curved surface and the 3rd curved surface, the light making this bundle be parallel to z-axis in space any one disk vertical with z-axis is forming uniform Illumination Distribution after the 5th curved surface; And the 4th curved surface, be the face of cylinder, for connecting the 3rd curved surface and the 5th curved surface;

Described free-form surface reflector, be made up of three curved surfaces, wherein first surface is free form surface, controls direction and the energy of the light beam that the second free-form surface lens sends, and the second curved surface and the 3rd curved surface are respectively the first pedestal and second pedestal of reflector.

Further, the coordinate described first surface and the second curved surface put is calculated by following formula: the initial point setting the first free form surface, obtains its outline line by following formula iteration:

$\left\{\begin{array}{c}{x}_i=\frac{z_{i-1}+x_{i-1}k}{\cot {\mathrm{\θ}}_i+k}\\ z_i=x_i\cot {\mathrm{\θ}}_i\end{array}\right.---\left(1\right)$

Wherein (x _i, z _i) be the coordinate of the calculative point of current iteration, (x _i-1, z _i-1) be more front coordinate, (N _x, N _z) be more front normal vector coordinate.The first free form surface can be obtained with z-axis position symmetry axis rotating 360 degrees after obtaining contour curve.

Again further, the x that described 5th curved surface is put, y-axis coordinate are identical with corresponding points on first surface, the second curved surface and the 3rd curved surface, the angular region of light source is divided into M × N part, luminous flux in every part is identical, calculate x, the y-axis coordinate of the 5th corresponding curved surface, emergent light spot is formed the unit that equally distributed disk is divided into M × N number of area equation simultaneously, and calculate x, the y-axis coordinate of these cell nodes, the initial point of selected curved surface, solving by the method for iteration the z-axis coordinate that initial scaffold curve is put is:

$z_{1,i}=\frac{-(x_{1,i}-x_{1,i-1})N_{1x}-(y_{1,i}-y_{1,i-1})N_{1y}}{N_{1z}}+z_{1,i-1}---\left(2\right)$

Wherein (x _{1, i}, y _{1, i}, z _{1, i}) be the coordinate of the calculative point of current iteration, (x _{1, i-1}, y _{1, i-1}, z _{1, i-1}) be upper coordinate, (N _1x, N _1y, N _1z) be the coordinate of upper normal vector.After obtaining initial scaffold curve, obtain next skeleton curve by (2) formula iteration, after obtaining all skeleton curves, obtain all subsurfaces by the mode of setting-out thus obtain the 5th curved surface.

Again further, the free form surface of described free-form surface reflector is made up of necessarily multiple subsurfaces, and connected by the plane being parallel to z-axis between two adjacent subsurfaces, target face divided, the node coordinate of division is (T _x, T _y, T _z), the initial point of selected curved surface, solving by the method for iteration the z-axis coordinate that initial scaffold curve is put is:

$\left\{\begin{array}{c}{x}_{2,i}=\mathrm{lx}(z_{2,i}-z_{1,i})+x_{1,i}\\ y_{2,i}=\mathrm{ly}(z_{2,i}-z_{1,i})+y_{1,i}\\ z_{2,i}=\frac{((\mathrm{lx}\×z_{1,i}-x_{1,i}+x_{2,i-1})N_{2,x}+(\mathrm{ly}\×z_{1,i}-y_{1,i}+y_{2,i-1})N_{2,y}+z_{2,i-1}{N}_{2,z})}{\mathrm{lx}\×N_{2,x}+\mathrm{ly}\×N_{2,y}+N_{2,z}}\end{array}\right.---\left(3\right)$

Wherein (x _{2, i}, y _{2, i}, z _{2, i}) be the coordinate of the calculative point of current iteration, (x _{2, i-1}, y _{2, i-1}, z _{2, i-1}) be more front coordinate, (N _2x, N _2y, N _2z) be more front normal vector coordinate, (x _{1, i}, y _{1, i}, z _{1, i}) be the coordinate of corresponding points on free-form surface lens the 5th free form surface.The expression formula of lx and ly is:

$\left\{\begin{array}{c}\mathrm{lx}=\frac{T_{x,i}-x_{1,i}}{T_{z,i}-z_{1,i}}\\ \mathrm{ly}=\frac{T_{y,i}-y_{1,i}}{T_{z,i}-z_{1,i}}\end{array}\right.---\left(4\right)$

Next skeleton curve is obtained by (2) formula iteration after obtaining initial scaffold curve, initial scaffold curve is re-constructed at the section start of each subsurface, after obtaining all skeleton curves, obtain all subsurfaces by the mode of setting-out, obtain the free form surface of free-form surface reflector.

Design LED secondary optical system of the present invention, has good light control ability, can realize required Illumination Distribution in target face.Owing to adopting the design of Zigzag type, be equivalent to the area expanding light source, reduce the brightness value of light source, therefore do not have the phenomenon of " dazzling ".Because reflecting surface does not exist total reflection phenomenon, therefore can realize the illumination of any angle of visual field, and the light efficiency of optical system can not be reduced because of total reflection.Simultaneously owing to adopting free-form surface lens to carry out collection and shaping to the light of LED, solve only to have in the optical system of reflecting surface to exist and block or the uncontrollable problem of a part of light.

Accompanying drawing explanation

Fig. 1 is the side view of one embodiment of the invention;

The side view of free-form surface lens (1) in Fig. 2 Fig. 1;

The sectional view of Fig. 3 Fig. 2;

Fig. 4 is the side view of free-form surface reflector in Fig. 1 (2);

Fig. 5 is the sectional view of Fig. 4;

The grid corresponding relation that Fig. 6 uses when being and calculating coordinate on free-form surface reflector (2);

Fig. 7 is that the present embodiment obtains Illumination Distribution simulation result in target face in optical design software; Free-form surface lens (1) and free-form surface reflector (2)

In figure, 1-free-form surface lens, 11-first surface; 12-second curved surface; 13-the 3rd curved surface; 14-the 4th curved surface; 15-the 5th curved surface; 2-free-form surface reflector; 21-free form surface; 22-first pedestal; 23-second pedestal.

Detailed description of the invention

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail:

Zigzag type LED illumination optical system comprises free-form surface lens 1 and free-form surface reflector 2, free-form surface lens 1 and free-form surface reflector 2 coaxial, spacing is 0.01m-0.1m; Free-form surface lens 1 comprises first surface 11, is Rotational Symmetry free form surface, for the light refraction sent by LED, makes the light ray parallel after refraction in z-axis; Second curved surface 12 is Rotational Symmetry free form surface, for the light refraction sent by LED, makes the light after refraction become the light sent with spot light in x-axis and overlaps; 3rd curved surface 13, for rotating parabola, paraboloidal focus is the virtual optical source point of the second curved refractive light, by direction extremely parallel with z-axis for the light reflection after reflecting through the second curved surface 12; 5th curved surface 15, for Rotational Symmetry free form surface, for controlling the light being parallel to z-axis after first surface 11, second curved surface 12 and the 3rd curved surface 13, the light making this bundle be parallel to z-axis in space any one disk vertical with z-axis is forming uniform Illumination Distribution after the 5th curved surface 15; And the 4th curved surface 14, be the face of cylinder, for connecting the 3rd curved surface 13 and the 5th curved surface 15; Free-form surface reflector 2, be made up of three curved surfaces, wherein first surface is free form surface 21, controls direction and the energy of the light beam that the second free-form surface lens 2 sends, and the second curved surface and the 3rd curved surface are respectively the first pedestal 22 and the second pedestal 23 of reflector.

On first surface 11 and the second curved surface 12, the coordinate of point is calculated by following formula: the initial point setting the first free form surface, obtains its outline line by following formula iteration:

$\left\{\begin{array}{c}{x}_i=\frac{z_{i-1}+x_{i-1}k}{\cot {\mathrm{\θ}}_i+k}\\ z_i=x_i\cot {\mathrm{\θ}}_i\end{array}\right.---\left(5\right)$

Wherein (x _i, z _i) be the coordinate of the calculative point of current iteration, (x _i-1, z _i-1) be more front coordinate, (N _x, N _z) be more front normal vector coordinate.The first free form surface can be obtained with z-axis position symmetry axis rotating 360 degrees after obtaining contour curve.

The x that 5th curved surface 15 is put, y-axis coordinate are identical with corresponding points on the 3rd curved surface 13 with first surface 11, second curved surface 12, the angular region of light source is divided into M × N part, luminous flux in every part is identical, calculate x, the y-axis coordinate of the 5th corresponding curved surface 15, emergent light spot is formed the unit that equally distributed disk is divided into M × N number of area equation simultaneously, and calculate x, the y-axis coordinate of these cell nodes, the initial point of selected curved surface, solving by the method for iteration the z-axis coordinate that initial scaffold curve is put is:

$z_{1,i}=\frac{-(x_{1,i}-x_{1,i-1})N_{1x}-(y_{1,i}-y_{1,i-1})N_{1y}}{N_{1z}}+z_{1,i-1}---\left(6\right)$

Wherein (x _{1, i}, y _{1, i}, z _{1, i}) be the coordinate of the calculative point of current iteration, (x _{1, i-1}, y _{1, i-1}, z _{1, i-1}) be upper coordinate, (N _1x, N _1y, N _1z) be the coordinate of upper normal vector.After obtaining initial scaffold curve, obtain next skeleton curve by (2) formula iteration, after obtaining all skeleton curves, obtain all subsurfaces by the mode of setting-out thus obtain the 5th curved surface 15.

The free form surface 21 of free-form surface reflector 2 is made up of necessarily multiple subsurfaces, and connected by the plane being parallel to z-axis between two adjacent subsurfaces, target face divided, the node coordinate of division is (T _x, T _y, T _z), the initial point of selected curved surface, solving by the method for iteration the z-axis coordinate that initial scaffold curve is put is:

$\left\{\begin{array}{c}{x}_{2,i}=\mathrm{lx}(z_{2,i}-z_{1,i})+x_{1,i}\\ y_{2,i}=\mathrm{ly}(z_{2,i}-z_{1,i})+y_{1,i}\\ z_{2,i}=\frac{((\mathrm{lx}\×z_{1,i}-x_{1,i}+x_{2,i-1})N_{2,x}+(\mathrm{ly}\×z_{1,i}-y_{1,i}+y_{2,i-1})N_{2,y}+z_{2,i-1}{N}_{2,z})}{\mathrm{lx}\×N_{2,x}+\mathrm{ly}\×N_{2,y}+N_{2,z}}\end{array}\right.---\left(7\right)$

Wherein (x _{2, i}, y _{2, i}, z _{2, i}) be the coordinate of the calculative point of current iteration, (x _{2, i-1}, y _{2, i-1}, z _{2, i-1}) be more front coordinate, (N _2x, N _2y, N _2z) be more front normal vector coordinate, (x _{1, i}, y _{1, i}, z _{1, i}) be the coordinate of corresponding points on free-form surface lens the 5th free form surface.The expression formula of lx and ly is:

$\left\{\begin{array}{c}\mathrm{lx}=\frac{T_{x,i}-x_{1,i}}{T_{z,i}-z_{1,i}}\\ \mathrm{ly}=\frac{T_{y,i}-y_{1,i}}{T_{z,i}-z_{1,i}}\end{array}\right.---\left(8\right)$

Next skeleton curve is obtained by (2) formula iteration after obtaining initial scaffold curve, initial scaffold curve is re-constructed at the section start of each subsurface, after obtaining all skeleton curves, obtain all subsurfaces by the mode of setting-out, obtain the free form surface 21 of free-form surface reflector 2.

Be the structural representation of a specific embodiment of the present invention as shown in Figure 1, wherein LED is positioned at the origin of coordinates, and this optical system comprises two parts, free-form surface lens 1 and free-form surface reflector 2.

Fig. 2 and Fig. 3 is side-looking and the sectional view of free-form surface lens 1 in Fig. 1.Wherein first surface 11, second curved surface 12 and the 3rd curved surface 13 are planes of incidence of LED light line, and object is the spherical wave collimation sent by LED is the plane wave vertical with z-axis.

First surface 11 is by the light refraction from LED to parallel with z-axis, and this curved surface is rotational symmetric, only need calculate a contour curve when therefore calculating, and then revolves to turn around around z-axis to obtain the face type of first surface 11.When calculating contour curve, first determine the coordinate value of initial point, initial point is the intersection point of curved surface and z-axis, is calculated the coordinate value that contour curve is put by the mode of iteration.Make current known point (x _i-1, z _i-1) normal vector be N=(N _x, N _z), incident ray a bit corresponding under the contour curve that calculate and the angle of z-axis are θ _i, then coordinate value (the x of any is descended _i, z _i) be:

$\left\{\begin{array}{c}{x}_i=\frac{z_{i-1}+x_{i-1}k}{\cot {\mathrm{\θ}}_i+k}\\ z_i=x_i\cot {\mathrm{\θ}}_i\end{array}\right.---\left(9\right)$

Wherein k=N _x/ N _z.In this implements, the z coordinate value of the initial point of first surface 11 is 5mm, and the corresponding LED light line of curved edges and z-axis angle are 30 °.

The object of the second curved surface 12 is that the reverse extending line of the emergent ray of light after this curved refractive that LED is sent meets at x-axis a bit, thus can obtain a virtual optical source point.The initial point of S12 is the marginal point of S11, uses equally (1) during calculating.

The focus of the 3rd curved surface 13 is the virtual optical source point that the second curved surface 12 is created, and utilizes total reflection principle, by from the second curved surface 12 light reflection to z-axis parallel direction.

Being redistributed by the energy of the plane wave after first surface 11, second curved surface 12 and the 3rd curved surface 13 of 5th curved surface 15, makes certain center in space be formed in z-axis and on the disk vertical with z-axis and is uniformly distributed.On 4th curved surface 14, the coordinate account form of point is for utilizing the conservation of energy, incident wavefront and target circle plane are divided into the equal grid of energy, according to the corresponding relation between space topological determination mesh point, recycling (1) formula can calculate the coordinate of point on the 5th curved surface 15.Because the 5th curved surface 15 is rotational symmetric, therefore only need to calculate contour curve and can obtain curved surface face type.In this enforcement, this disk is positioned at z=80mm place, and radius is 20mm, and the initial point of free form surface S15 is (0,0,21.36).

4th curved surface 14 is the face of cylinder, for connecting the 3rd curved surface 13 and the 5th curved surface 15.

After all curved surfaces calculating free-form surface lens 1, height is 24.27mm, and wide is 32.44mm.The space height formed between first surface 11, second curved surface 12 is 5mm, and wide is 4.9mm, for placing LED light source.

Fig. 4 and Fig. 5 is side-looking and the sectional view of free-form surface reflector 2 in Fig. 1.Reflector in this enforcement is made up of first surface 11, second curved surface 12 and the 3rd curved surface 13.

First pedestal 22 and the second pedestal 23 are the pedestal of free-form surface reflector 2, can have any shape in actual use, in this enforcement, and these two Surface formings column type pedestal.

The object of free form surface 21 is that the beam reflection from free-form surface lens 1 is formed uniform illuminance to target face in target face.In this enforcement, set target face is that the length of side is 8m × 6m and the rectangle vertical with y-axis, and target face central point to be positioned in y-axis and apart from LED light source 2.5m.The conservation of energy and Snell's law is adopted to calculate the coordinate that free form surface is put.First according to the conservation of energy, the target circle plane of setting during design the 5th curved surface 15 and illumination target face are divided into the equal grid of energy as shown in Figure 6, due to symmetry, only give the stress and strain model corresponding relation of first quartile here.According to Snell's law after obtaining this corresponding relation, the central point of the target circle plane of setting when setting initial point is design the 5th curved surface 15, adopts the mode of iteration to obtain the coordinate of point on free form surface 21.In order to reduce the error produced in an iterative process, adopting the mode of patch to construct free form surface 21, between each patch, using the face of cylinder to connect.

In order to construct free form surface 21, target face is done the division shown in Fig. 6, the node coordinate of division is (T _x, T _y, T _z).The initial point of selected curved surface, solving by the method for iteration the z-axis coordinate that initial scaffold curve is put is:

$\left\{\begin{array}{c}{x}_{2,i}=\mathrm{lx}(z_{2,i}-z_{1,i})+x_{1,i}\\ y_{2,i}=\mathrm{ly}(z_{2,i}-z_{1,i})+y_{1,i}\\ z_{2,i}=\frac{((\mathrm{lx}\×z_{1,i}-x_{1,i}+x_{2,i-1})N_{2,x}+(\mathrm{ly}\×z_{1,i}-y_{1,i}+y_{2,i-1})N_{2,y}+z_{2,i-1}{N}_{2,z})}{\mathrm{lx}\×N_{2,x}+\mathrm{ly}\×N_{2,y}+N_{2,z}}\end{array}\right.---\left(10\right)$

Wherein (x _{2, i}, y _{2, i}, z _{2, i}) be the coordinate of the calculative point of current iteration, (x _{2, i-1}, y _{2, i-1}, z _{2, i-1}) be more front coordinate, (N _2x, N _2y, N _2z) be more front normal vector coordinate, (x _{1, i}, y _{1, i}, z _{1, i}) be the coordinate of corresponding points on free form surface 21.The expression formula of lx and ly is:

$\left\{\begin{array}{c}\mathrm{lx}=\frac{T_{x,i}-x_{1,i}}{T_{z,i}-z_{1,i}}\\ \mathrm{ly}=\frac{T_{y,i}-y_{1,i}}{T_{z,i}-z_{1,i}}\end{array}\right.---\left(11\right)$

Next skeleton curve is obtained by (2) formula iteration after obtaining initial scaffold curve.Initial scaffold curve is re-constructed at the section start of each subsurface.After obtaining all skeleton curves, obtain all subsurfaces by the mode of setting-out thus obtain free form surface 21.

Fig. 7 is the Illumination Distribution result of lens in optical simulation software in target face of this enforcement, obtained by trace 1,000,000 light, wherein left side is the Illumination Distribution in target face, in figure, gray value size is directly proportional to brightness value, and right side is the Illumination Distribution in target face on two centre coordinate axles.Wherein the optical efficiency of optical system is 80%.Illumination uniformity simultaneously in target face on long limit and minor face is 75% and 70%, and uniformity is good.

Claims (3)

1. a Zigzag type LED illumination optical system, it is characterized in that: comprise free-form surface lens (1) and free-form surface reflector (2), described free-form surface lens (1) and free-form surface reflector (2) coaxial, spacing is 0.01m-0.1m;

Described free-form surface lens (1) comprises first surface (11), is Rotational Symmetry free form surface, for the light refraction sent by LED, makes the light ray parallel after refraction in z-axis; Second curved surface (12) is Rotational Symmetry free form surface, for the light refraction sent by LED, makes the light after refraction become the light sent with spot light in x-axis and overlaps; 3rd curved surface (13), for rotating parabola, paraboloidal focus is the virtual optical source point of the second curved refractive light, by the light reflection after the second curved surface (12) refraction to the direction parallel with z-axis; 5th curved surface (15), for Rotational Symmetry free form surface, for controlling to be parallel to the light of z-axis after first surface (11), the second curved surface (12) and the 3rd curved surface (13), the light this being restrainted be parallel to z-axis in space any one disk vertical with z-axis is forming uniform Illumination Distribution after the 5th curved surface (15); And the 4th curved surface (14), be the face of cylinder, for connecting the 3rd curved surface (13) and the 5th curved surface (15);

Described free-form surface reflector (2), be made up of three curved surfaces, wherein first surface is free form surface (21), control direction and the energy of the light beam that the second free-form surface lens (2) sends, the second curved surface and the 3rd curved surface are respectively the first pedestal (22) and second pedestal (23) of reflector;

The coordinate of described first surface (11) and the upper point of the second curved surface (12) is calculated by following formula: the initial point setting the first free form surface, obtains its outline line by following formula iteration:

$\left\{\begin{array}{c}{x}_i=\frac{z_{i-1}+x_{i-1}k}{{\mathrm{cot\θ}}_i+k}\\ z_i=x_i{\mathrm{cot\θ}}_i\end{array}\right.---\left(1\right)$

Wherein (x _i, z _i) be the coordinate of the calculative point of current iteration, (x _i-1, z _i-1) be more front coordinate, (N _x, N _z) be more front normal vector coordinate.The first free form surface can be obtained with z-axis position symmetry axis rotating 360 degrees after obtaining contour curve.

2. Zigzag type LED illumination optical system according to claim 1, it is characterized in that: the x of the upper point of described 5th curved surface (15), y-axis coordinate and first surface (11), second curved surface (12) is identical with the upper corresponding points of the 3rd curved surface (13), the angular region of light source is divided into M × N part, luminous flux in every part is identical, calculate the x of the 5th corresponding curved surface (15), y-axis coordinate, emergent light spot is formed the unit that equally distributed disk is divided into M × N number of area equation simultaneously, and calculate the x of these cell nodes, y-axis coordinate, the initial point of selected curved surface, solving by the method for iteration the z-axis coordinate that initial scaffold curve is put is:

$z_{1,i}=\frac{-(x_{1,i}-x_{1,i-1})N_{1x}-(y_{1,i}-y_{1,i-1})N_{1y}}{N_{1z}}+z_{1,i-1}---\left(2\right)$

Wherein (x _{1, i}, y _{1, i}, z _{1, i}) be the coordinate of the calculative point of current iteration, (x _{1, i-1}, y _{1, i-1}, z _{1, i-1}) be upper coordinate, (N _1x, N _1y, N _1z) be the coordinate of upper normal vector.After obtaining initial scaffold curve, obtain next skeleton curve by (2) formula iteration, after obtaining all skeleton curves, obtain all subsurfaces by the mode of setting-out thus obtain the 5th curved surface (15).

3. Zigzag type LED illumination optical system according to claim 1, it is characterized in that: the free form surface (21) of described free-form surface reflector (2) is made up of necessarily multiple subsurfaces, connected by the plane being parallel to z-axis between two adjacent subsurfaces, target face divided, the node coordinate of division is (T _x, T _y, T _z), the initial point of selected curved surface, solving by the method for iteration the z-axis coordinate that initial scaffold curve is put is:

$\left\{\begin{array}{c}{x}_{2,i}=lx(z_{2,i}-z_{1,i})+x_{1,i}\\ y_{2,i}=lx(z_{2,i}-z_{1,i})+y_{1,i}\\ z_{2,i}=\frac{\left(\right(lx\×z_{1,i}-x_{1,i}+x_{2,i-1})N_{2,x}+(ly\×z_{1,i}-y_{1,i}+y_{2,i-1})N_{2,y}+z_{2,i-1}{N}_{2,z})}{lx\×N_{2,x}+ly\×N_{2,y}+N_{2,z}}\end{array}\right.---\left(3\right)$

Wherein (x _{2, i}, y _{2, i}, z _{2, i}) be the coordinate of the calculative point of current iteration, (x _{2, i-1}, y _{2, i-1}, z _{2, i-1}) be more front coordinate, (N _2x, N _2y, N _2z) be more front normal vector coordinate, (x _{1, i}, y _{1, i}, z _{1, i}) be the coordinate of corresponding points on free-form surface lens the 5th free form surface.The expression formula of lx and ly is:

$\{\begin{array}{c}lx=\frac{T_{x,i}-x_{1,i}}{T_{z,i}-z_{1,i}}\\ ly=\frac{T_{y,i}-y_{1,i}}{T_{z,i}-z_{1,i}}\end{array}---\left(4\right)$

Next skeleton curve is obtained by (2) formula iteration after obtaining initial scaffold curve, initial scaffold curve is re-constructed at the section start of each subsurface, after obtaining all skeleton curves, obtain all subsurfaces by the mode of setting-out, obtain the free form surface (21) of free-form surface reflector (2).