CN203848200U - Lens and lens system - Google Patents

Abstract

The utility model discloses a lens and a lens system and application thereof. The lens comprises a front surface, a rear surface and a side surface extending between the front surface and the rear surface, a cavity facing the rear portion is limited by the rear surface, the front surface comprises a central surface and an edge surface surrounding and connected with the central surface, and the edge surface extends between the central surface and the side surface. The lens is an axisymmetric body, and a central axis is limited by the lens. The lens is matched with an LED light source or/and a similar light source disposed on the central axis and capable of moving in the cavity to form the lens system. High utilization rate of emergent light of the light source is realized, and collimation and focusing of incident light are realized as well.

Description

A kind of lens and lens system

technical field

The utility model relates to an optical device, in particular to a lens, a lens system and its application.

Background technique

With the continuous development of semiconductor materials and processes, light-emitting diodes (LEDs) are gradually replacing traditional light sources. This is due to the special light-emitting principle of light-emitting diodes, which consumes far less energy than ordinary incandescent lamps when achieving the same brightness, and has the advantages of long life and no pollution, and has broad prospects in the field of lighting and backlighting. .

In LED lighting products, in order to obtain proper light distribution and light intensity, it is often necessary to install a lens in front of the LED lamp bead to achieve light convergence. For example, a Fresnel lens can emit light from its focus. The light turns into parallel light.

In addition, in order to further make full use of the LED light, the current mainstream method is to arrange a cavity on the lens, and arrange the LED light source in the cavity. Because the light emitted by the LED as a point light source is distributed in a 180-degree space, using the above method can theoretically make all the light emitted by the LED enter the lens, and then adjust the outgoing direction of the incident light according to the structure of the lens. In order to achieve convergence, uniform light and other effects.

In some use cases, there is also a requirement for the exit light spot, which can usually be achieved by adjusting the relative position of the LED light source and the lens.

To realize all the requirements mentioned above, it is necessary to obtain the shape of the lens through accurate simulation calculation. At present, such lenses generally have a front surface, a side surface, and a rear surface, and the rear surface defines a cavity as a placement area for the LED light source, so that all light emitted by the LED can be confined in the cavity. At this time, it is necessary to calculate and deduce the arc shape of the front surface, rear surface and side surface according to the designed optical path, which also involves the cooperation between each surface, which is particularly important for realizing the optical path control of light.

Under the premise of not considering the cost of lens materials, the above design is relatively easy to realize. With the further consideration of the cost of the lens, various more material-saving product designs continue to be produced, which mainly achieve material saving by reducing the distance between the front surface and the rear surface, that is, making the lens thinner. There are even higher requirements for the arc shape accuracy of the front surface, the rear surface and the side surface and their mutual cooperation, so that the design is more difficult and the design cycle is longer.

Similarly for lens processing, the more processing surfaces that require precise control or are more difficult to process, the more difficult it is to prepare the lens, which directly affects the yield of the product.

Therefore, those skilled in the art are committed to developing a light source that can achieve high utilization of light from LED light sources (or light sources similar to LEDs), has convergence and focusing functions, and is material-saving, simple in structure, and reduces as much as possible. High precision requires lenses with optical surfaces.

Utility model content

In order to achieve the above purpose, the utility model provides a lens, a lens system coordinating with a light source with the lens and its application.

a lens comprising a front surface, a back surface, and a side surface extending between the front surface and the back surface, the front surface being at the front of the lens, and the back surface being at the back of the lens; The rear surface defines a cavity facing the rear; the front surface includes a central surface, and edge surfaces surrounding and connecting the central surface, the edge surfaces extending between the central surface and the side surfaces; The lens defines a central axis; the cavity includes side walls and a bottom, the side walls and the bottom define a cavity space, the central axis passes through the central surface and the bottom; the edge surfaces are at The corresponding line segment on the central cross-section, ie, the edge line segment, is composed of alternately connected line segments parallel to the central axis and line segments perpendicular to the central axis, similar to a right-angled ladder shape.

Further, any cross-section of the lens passing through the central axis, that is, the central cross-section, has the same figure, which defines that the lens is an axisymmetric body, and the central axis is the central axis

Further, the line segment corresponding to the central surface on the central cross-section, that is, the central line segment, is in the form of an arc. Alternatively, the central surface is an arcuate surface.

Further, the arc convex direction of the central line segment is away from the bottom, that is, the central surface protrudes toward the front of the lens.

Further, the extension direction of the edge line segment parallel to the central axis is the same as the arc-shaped convex direction of the central line segment, and the edge line segment extends away from the central line segment in a direction perpendicular to the central axis. That is, the peripheral surface and the central surface generally form a bowl shape, and the opening of the bowl is located at the front of the lens, opposite the opening of the cavity.

Further, the corresponding line segment of the side wall on the central cross section, that is, the line segment of the side wall, is in the form of a straight line or an arc.

Further, the line segment of the side wall is parallel to the central axis, that is, the side wall is cylindrical.

Further, the bottom is an arc or a plane. When the bottom is an arc, the convex direction of the arc is not limited, and may be the same as or opposite to that of the central surface. The principle is that the bottom cooperates with the central surface to form a convex lens or to achieve the effect of a convex lens.

Further, the side wall is matched with the side surface so that: the incident light emitted by the point light source located on the central axis enters the lens through the side wall, and the reflected light reflected by the side surface is parallel to on the central axis. Under the condition that the refractive index of the lens and the position of the light source are determined, the corresponding curve of the side surface on the central cross-section is deduced by mathematical methods for the refraction and reflection light path of the light, and the curve equation is obtained, thereby determining the curved surface of the side surface shape.

Further, the size of the edge surface satisfies that: the reflected light reflected by the side surface is directly emitted from the edge surface. The reflected light combined with the side surface is parallel to the central axis, and the outgoing light of the edge surface is a collimated beam at this time.

Further, the shape of the side surface satisfies: the side surface totally reflects the incident light entering through the side wall.

Further, the central surface cooperates with the bottom so that: the incident light emitted by the point light source located on the central axis enters the lens from the bottom, and the corresponding outgoing light only emerges from the central surface . In the case that the refractive index of the lens is determined, the size combination of the central surface and the bottom can be obtained simply through the refractive index equation.

Further, the shape of the edge surface satisfies: the outgoing light emitted from the central surface will not be blocked by the edge surface. That is, the step heights of the edge surfaces do not block the outgoing light from the central surface.

Further, the side surface is coated with a total reflection film.

Further, the total reflection film is silver.

Further, the material of the lens is polymethyl methacrylate (PMMA).

A lens system using the above-mentioned lens includes the lens and a light source, and the light source provides incident light to the lens.

Further, the light source is on the central axis of the lens.

Further, the light source can move along the central axis.

Further, the moving range of the light source is inside the cavity of the lens, including the position where the distance from the cavity is 0.

Further, the moving range of the light source is 0 mm from the cavity to 10 mm deep into the cavity.

Further, when the light source moves from 0 mm away from the cavity to 10 mm deep into the cavity, the maximum included angle of the outgoing light emitted from the central surface of the lens is 8-90 degrees.

Further, the light source is an LED light source, or a light source similar to an LED, that is, a light source that has good monochromaticity and emits light that is distributed in a 180-degree space.

The lens system described above can be used in a flashlight with an adjustable focus function.

The lens and lens system of the present utility model have the following advantages:

1. It can make full use of LED light source (or LED-like light source) to emit light, realizing high utilization rate of light energy;

2. The outgoing light is divided into collimated outgoing light and adjustable outgoing light. The ratio of the two parts of outgoing light can be easily adjusted in design to meet different use requirements;

3. The adjustable spot range is large, which can meet various application requirements;

4. The optical surface with high processing accuracy or difficulty has only the side surface, thereby reducing the difficulty of manufacturing.

5. The lens is similar to a bowl shape, which saves production materials.

Description of drawings

Fig. 1 is the front view of a preferred embodiment of the lens of the present utility model;

Fig. 2 is a sectional view along A-A direction in Fig. 1;

Fig. 3 is a schematic diagram of the incident and outgoing rays of the collimated rays of the lens shown in Fig. 2, only showing the rays on the right side of the central axis;

Fig. 4 is a schematic diagram of incident and outgoing of all collimated rays of the lens shown in Fig. 2;

Fig. 5 is a schematic diagram of the incident and outgoing light rays partially focused by the lens shown in Fig. 2. The light source is located outside the cavity of the lens, and only the light rays on the right side of the central axis are shown;

Fig. 6 is a schematic diagram of incident and outgoing light of all focused light rays of the lens shown in Fig. 2, and the light source is located outside the cavity of the lens;

Fig. 7 is a schematic diagram of the incident and outgoing rays of the focused light part of the lens shown in Fig. 2, the light source is located in the cavity of the lens, and only the light beam on the right side of the central axis is shown;

Fig. 8 is a schematic diagram of incident and outgoing light of all focused light rays of the lens shown in Fig. 2, and the light source is located in the cavity of the lens;

Fig. 9 is a schematic diagram of the incidence and exit of all light rays of the lens shown in Fig. 2, and the light source is located in the cavity of the lens;

Fig. 10 is the calculated coordinate diagram of the corresponding curve on the central cross-section of the side surface of the lens shown in Fig. 2;

Fig. 11 is a schematic diagram of the critical point of the corresponding curve on the central cross-section of the side surface of the lens shown in Fig. 2;

Fig. 12 is a schematic diagram of another preferred embodiment of the lens of the present invention, the convex direction of the arc surface at the bottom is away from the central surface;

Fig. 13 is a schematic diagram of another preferred embodiment of the lens of the present invention, the bottom is a plane;

Fig. 14 is a schematic diagram of a preferred embodiment of the flashlight adopting the lens system of the present invention, the LED light source is at the mouth of the lens;

Fig. 15 is a schematic diagram of the LED light source of the flashlight shown in Fig. 14 being in the cavity of the lens.

Detailed ways

The conception, specific structure and technical effects of the present utility model will be further described below in conjunction with the accompanying drawings, so as to fully understand the purpose, characteristics and effects of the present utility model.

Lens 1 as shown in Figure 1 and Figure 2, comprises front surface 2, back surface 3, and the side surface 4 that extends between front surface 2 and back surface 3; Back surface defines the cavity 5 facing rear; Front The surface 2 includes a central surface 201, and an edge surface 202 surrounding and connecting the central surface 201, the edge surface 202 extends between the central surface 201 and the side surface 4; the lens 1 defines a central axis 6, and the lens 1 passes through any transverse direction of the central axis 6. The cross-section, that is, the central cross-section, has the same figure, which defines that the lens 1 is an axisymmetric body, and the central axis is the central axis 6; the cavity 5 includes a side wall 501 and a bottom 502, and the side wall 501 and the bottom 502 define the cavity space , the central axis 6 passes through the central surface 201 and the bottom 502; the corresponding line segment of the edge surface 202 on the central cross-section, that is, the edge line segment 204, is alternately connected by a line segment parallel to the central axis 6 and a line segment perpendicular to the central axis 6 composition. Similar to the right-angled stepped shape, that is, the line segment corresponding to the edge surface 202 on the central cross-section is a stepped line segment, which is composed of a plurality of line segments connected parallel or perpendicular to the central axis 6 .

The corresponding line segment of the central surface 201 on the central cross-section, that is, the central line segment 203, is an arc, which defines that the central surface 201 is a symmetrical arc along the central axis 6, and in this embodiment the arc is a spherical surface , the protruding direction of which is opposite to the opening direction of the cavity 5 and the same as the extending direction of the edge surface 202 along the central axis 6 . At the same time, the extension of the edge surface 202 perpendicular to the central axis 6 is away from the central surface 201 . The side wall 501 of the chamber 5 is parallel to the central axis 6, that is, the side wall 501 is cylindrical.

The lens 1 needs to be used with a light source located on the central axis 6. The following uses a point light source as an example to further illustrate the characteristics of the lens 1. As shown in Figures 3 and 4, the point light source 7 located on the central axis 6 provides incident light. The incident light entering the lens 1 from the wall 501 , the reflected light reflected by the side surface 4 is parallel to the central axis 6 , and finally the reflected light is emitted from the edge surface 202 . Since the edge surface 202 only includes an annulus perpendicular to and parallel to the central axis 6 , the outgoing light emitted from the edge surface 202 is also parallel to the central axis 6 , realizing collimated emission of the incident light. Using the side wall 501 and edge surface 202 with the above-mentioned topography, and on the premise that the lens material (refractive index) is determined, the design only needs to accurately calculate the arc shape of the side surface 4 to realize the above-mentioned collimation function, and at the same time Total reflection is realized on the side surface 4 (the derivation calculation method for the side surface 4 will be described in detail below). In terms of processing difficulty, the side wall 501 and the edge surface 202 of the lens 1 only include surfaces perpendicular or parallel to the central axis 6, and the processing is relatively simple, and only the side surface 4 needs to be strictly controlled, which greatly reduces the optical factors influencing each other.

On the premise that the lens material (refractive index) is determined, in order to achieve the total reflection of the side surface 4, there will be certain restrictions on the shape of the side surface 4, so for some specific size requirements, it may not be able to meet the requirements of the side surface 4 during design. The total reflection is realized on the surface 4. At this time, a total reflection film, such as silver, can be plated on the side surface 4.

As shown in FIGS. 5-8 , the point light source 7 is located on the central axis 6 , and the point light source 7 can move to the inside of the cavity 5 along the central axis 6 . For the incident light entering the lens 1 from the bottom 502, under the premise that the lens material (refractive index) is determined, various size combinations of the central surface 201 and the bottom 502 can be obtained from the refraction equation, so as to achieve the corresponding outgoing light from the center Surface 201 shoots out. In this embodiment, the central surface 201 and the bottom 502 are a spherical surface and an elliptical spherical surface respectively, and have the same convex direction, forming a convex lens together to converge the incident light so that the outgoing light forms a uniform spot within a certain range. At this time, the shape of the edge surface 202 (or the step height of the stepped structure) needs to be satisfied, and the outgoing light emitted from the central surface 201 cannot be blocked. When the point light source 7 gradually penetrates into the cavity 5, the maximum included angle of the outgoing light also increases accordingly, realizing the adjustment of the size of the light spot.

FIG. 9 shows a complete ray diagram in which the emitted light from the light source 7 is focused and collimated by the lens 1 .

Figure 10 is a coordinate diagram of the corresponding curve equation of the side surface in the central cross-section, wherein the Y-axis is the central axis, and also includes the optical path 9, the curve 10 corresponding to the side surface in the central cross-section, and the side wall line segment parallel to the Y-axis 11. Angle a, b, c, d, the calculation method of the curve equation is described in detail below:

Set the lens parameters: r—the radius of the opening of the cavity at the bottom of the lens, R—the radius of the bottom of the lens, n—the refractive index of the lens.

Goal: Under the above parameter conditions, form the curve equation y=f(x) of total reflection collimated light

1. Find the equation of the tangent line where Pn point is located:

∵f′(x)=tand

∵(90°-c)+2d=180°

∴

$\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; \&Right\; Arrow;</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; a</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>$

Then the slope of the equation of the line passing through this point:

Substitute the coordinates of Pn(Xn,Yn), then the tangent line passing through Pn satisfies the equation:

It can be approximately considered that the neighbor point Pn+1 of Pn is also on the tangent.

2. The light equation of the point Pn+1:

∵y=tanc·(x-r)+rcota

∵ $\mathrm{no}\sin c=\sin b=\cos a\&Right\; Arrow;c=\arcsin \left(\frac{\cos a}{\mathrm{no}}\right)$

∴ $\mathrm{the\; y}=\mathrm{the\; tan}\left[\arcsin \left(\frac{\cos a}{\mathrm{no}}\right)\right](x-r)+r\cot a...\left(2\right)$

3. Constraints:

The limiting slope is determined by the critical angle of total reflection

So there are:

Since it is not easy to solve it directly, we might as well assume the limit case: when a→90°, we can obtain It can be totally reflected, which can be realized for commonly used PMMA and PC materials; when a→0°, it can be substituted: when n>1, the surface can be totally reflected, which is obviously true; let

The function decreases monotonically at 0<a<90°. Therefore, under the same refractive index n, if the curved surface can totally reflect the light with the initial incident angle a=θ, then it must also be able to completely reflect the light with a'=θ-Δθ (both θ and Δθ are greater than 0). reflection.

Judging from the previous special value, it is known that when a → 90°, total reflection can occur only if the refractive index is greater than 1.414. Therefore, total reflection will also occur for angles below 90°. The result of a → 0° verifies the reasoning correctness.

Therefore, this curve can produce total reflection for any initial incident angle a of light, and only the requirement of lens structure height needs to be considered during design.

4. Find the discrete solution of the curve equation:

Solve the equations of equations (1) and (2), take the coordinate of P0 as Pn, and take a=1° to substitute in, the equations about X and Y can be obtained.

Solving equations (3) and (4) can get P1(X1, Y1)

Take the coordinates of P1 (X1, Y1) as P0 again, and substitute a=2° into (1) and (2) to get a new system of equations

Similarly, solving equations (5) and (6) can get P2 (X2, Y2)

By analogy, a series of coordinates of point P can be obtained.

The discrete point P0->Pn, through statistical software, such as Excel, MATLAB, polynomial fitting into a curve equation: y=f(x).

It can also be solved by programming. The program example is as follows:

clear all;clc

%The Frist Step defines adjustable variables

r=6;% select the hole radius

R=8.5;% defines the radius of the bottom of the surface

n=1.49;% defines the refractive index of the material

angles=(90:-0.5:40);% defines the calculation angle range

%The Second Step defines intermediate variables

num=length(angles);

Y0=R;Z0=0;

for i=1:num

a(i)=(angles(i)*pi/180);

c(i)=asin(cos(a(i))/n);

k1(i)=tan((pi/2+c(i))/2);

k2(i)=tan(c(i));

end

Cyclic solution of %The Third Step equation

for i=1:num

syms y;

f1=k1(i)*(y-Y0)+Z0;

f2=k2(i)*(y-r)+r*cot(a(i));

f=f1-f2;

yy=solve(f);

y=double(yy);

z=k1(i)*(y-Y0)+Z0;

Y0=y;

Z0=z;

Py(i)=Y0;

Pz(i)=Z0;

end

%The Forth Step polynomial fitting aspheric coefficients

cftool

%Attention, set x=Py y=Pz when fitting.

As shown in Figure 11, the critical point 14 of the extension length of the curve 10 is determined by the optical path 12 and the curve 10, the optical path 12 is the light path generated by the incident light from the bottom of the side wall, which satisfies the refraction relation:

sinθ1=n×sinθ2, n is the refractive index of the lens, θ1 and θ2 are the incident angle and refraction angle of the light respectively. In order to meet the requirement that the incident light from the side wall can reach the side surface, the end point of the upward extension of the curve 10 should not be lower than the critical point 14 . Also critical point 14 defines the size of the edge surface.

Using the same method, the fit relationship between the central surface and the bottom can also be analyzed. At this time, it is necessary to analyze the incident light path of the light from the bottom far away from the edge of the central axis, so that the extension width of the central surface is sufficient to cover the refracted light in the light path, so that the incident light emitted by the point light source located on the central axis enters the lens from the bottom , then the corresponding outgoing light only emerges from the central surface.

The lens shape based on the present invention is not limited to the structures shown in the above-mentioned embodiments. Another possible lens shape is shown in FIG. 12 , where the convex direction of the arcuate surface of the bottom 502 is away from the central surface 201 . Another lens shape that can be used is shown in FIG. 13 , where the bottom 502 is a plane.

It should also be pointed out that the shape of the side wall 501 can also be changed arbitrarily, and the curve equation of the side wall line segment is considered in the calculation. Through the above calculation method, the matching side surface curved surface can also be calculated.

The above-mentioned various lenses are especially suitable for cooperating with LED light sources (or light sources similar to LEDs) to form a lens system, which can achieve higher light intensity utilization while achieving technical effects such as zooming and collimation. When the LED light source is set on the central axis 6 and the movable range is within the cavity 5 (including the distance from the cavity 5 is 0), the light emitted by the LED light source can be completely received by the side wall 501 and the bottom 502 . At the same time, by adjusting the position of the LED light source in the cavity 5 , the size of the outgoing light spot can be adjusted.

In a more specific embodiment, the material used in the lens is polymethyl methacrylate, the refractive index is 1.49, and the design realizes that when the moving range of the light source is 0-10mm deep in the cavity 5, the central surface 201 of the lens 1 emits The variation range of the maximum included angle of the outgoing light is 8-90 degrees.

The above-mentioned lens system can be used in a flashlight with an adjustable focus function as a light source and an optical element of the flashlight. As shown in Figure 14 and Figure 15, it is a flashlight using the lens system of the present invention, wherein the flashlight 15 includes a handle 17 and a lens barrel 18, both of which adopt a telescopic structure, so that they can be stretched and retracted between the limits . The lens 1 and the LED light source 16 are respectively fixed on the lens barrel 18 and the handle 17, and are relatively moved through the expansion and contraction between the lens barrel 18 and the handle 17, thereby realizing the focusing function. FIG. 14 and FIG. 15 respectively show that the LED light source 16 is located in the mouth and in the cavity of the lens 1 . The relative movement of the handle 17 and the lens barrel 18 is not limited to the above-mentioned manner, and the two can also adopt a screw structure to realize telescoping. Any connection mode that makes the lens 1 and the LED light source 16 relatively move can realize the focusing function of the flashlight.

The above-mentioned lens system can also be applied to other occasions that need to adjust the size of the light spot (or the occasions where the focus and astigmatism change interactively), such as the flash system of the camera, the stage lighting system, etc.

In addition, it should be pointed out that due to the influence of lens processing and flashlight assembly accuracy, and the size of the LED light source, in actual use, some of the collimated light cannot be collimated and emitted, which will cause light spots when the LED light source moves. There will be a bright ring that changes in size, which depends entirely on the actual processing and assembly accuracy and the selection of the size of the LED light source.

The preferred specific embodiments of the present utility model have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present utility model without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the utility model through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection defined by the claims .

Claims (23)

1. A lens, characterized in that the lens comprises a front surface, a back surface, and side surfaces extending between the front surface and the back surface; the back surface defines a rear-facing cavity; The front surface includes a central surface, and edge surfaces surrounding and connecting the central surface, the edge surfaces extending between the central surface and the side surfaces; the lens defines a central axis; the cavity includes side walls and a bottom, the side walls and the bottom define a cavity space, the central axis passes through the central surface and the bottom; the corresponding line segment of the edge surface on the central cross-section, the edge The line segment is composed of alternately connecting line segments parallel to the central axis and line segments perpendicular to the central axis. the 2 . The lens according to claim 1 , wherein any cross section of the lens passing through the central axis, that is, a central cross section, has the same figure. the 3. The lens according to claim 2, wherein the corresponding line segment of the central surface on the central cross-section, that is, the central line segment, is in the form of an arc. the 4. The lens according to claim 3, wherein the convex direction of the arc of the central line segment is away from the bottom. the 5. The lens according to claim 4, wherein the extension direction of the edge line segment parallel to the central axis is the same as the arc-shaped convex direction of the central line segment, and the edge line segment is perpendicular to the The central axis extends in a direction away from the central line segment. the 6. The lens according to any one of claims 1-5, wherein the corresponding line segment of the side wall on the central cross-section, that is, the line segment of the side wall, is in the form of a straight line or an arc. the 7. The lens of claim 6, wherein the sidewall line segment is parallel to the central axis. the 8. The lens according to claim 5, wherein the bottom is an arc or a plane. the 9. The lens according to claim 5, wherein the side wall is matched with the side surface to satisfy: the incident light emitted by a point light source located on the central axis enters the lens through the side wall The reflected light reflected by the side surface behind the lens is parallel to the central axis. the 10 . The lens according to claim 9 , wherein the size of the edge surface satisfies that the reflected light reflected by the side surface is directly emitted from the edge surface. 11 . the 11. The lens according to claim 10, wherein the shape of the side surface satisfies: the side surface totally reflects incident light entering through the side wall. the 12. The lens according to claim 11, wherein the central surface cooperates with the bottom to satisfy: the incident light emitted by a point light source located on the central axis enters the lens from the bottom, The corresponding outgoing light then only emerges from said central surface. the 13. The lens according to claim 12, wherein the shape of the edge surface satisfies that the outgoing light emitted from the central surface will not be blocked by the edge surface. the 14. The lens according to claim 1, wherein the side surface is coated with a total reflection film. the 15. The lens of claim 13, wherein the total reflection film is silver. the 16. The lens according to claim 1, wherein the material of the lens is polymethyl methacrylate. the 17. A lens system adopting any lens according to claims 9-16, characterized in that it comprises the lens and a light source, and the light source provides the incident light of the lens. the 18. The lens system of claim 17, wherein the light source is on a central axis of the lens. the 19. The lens system of claim 18, wherein the light source is movable along the central axis. the 20. The lens system of claim 19, wherein the range of movement of the light source is inside the cavity of the lens. the 21. The lens system according to claim 20, wherein the moving range of the light source is 0 mm from the cavity to 10 mm deep into the cavity. the 22. The lens system according to claim 21, wherein when the light source moves from 0 mm to 10 mm deep in the cavity, the maximum output light emitted from the central surface of the lens is The included angle is 8-90 degrees. the 23. The lens system of any one of claims 18-22, wherein the light source is an LED light source. the