CN101231377B - Optical lens - Google Patents

Abstract

The invention discloses an optical lens comprising a first lens and a second lens, which are arranged coaxially and symmetrically about the optical axis. The first lens has a positive diopter and comprises a first convex surface and a second convex surface, wherein the first convex surface faces to an object surface and the optical effect diameter is smaller than that of the second convex surface. The second lens has a negative diopter and comprises a third surface and a fourth surface, wherein the third surface is concave and faces to the object surface and the fourth surface is convex. The dispersion value of the first lens is larger than that of the second lens, and the refractive index of the first lens is smaller than that of the second lens. The inventive optical lens can ensure good imaging quality with low cost.

Description

A kind of optical lens

Technical field

The present invention relates to optical device, relate in particular to a kind of optical lens.

Background technology

Optical lens is the significant components of digital image-forming equipment, and in recent years, camera has been standard configuration in the low and middle-end mobile phone, and how can reduce production costs as much as possible in the picture element that guarantees camera lens has become the focus of optical lens design.Simultaneously mobile phone day by day to frivolous, also force lens design to pursue shorter optics length overall.The needs of the large quantities of volume productions of modern industry require optical design not only will pursue better image quality, better processibility will be arranged, and adapt to the operability of back segment operation, can effectively improve yield, reduce production costs.This makes optical lens will meet following characteristics as far as possible:

1. good image quality.Centering particularly, low frequency have good optical transfer function (MTF) figure line;

2. small and exquisite, frivolous.Promptly require total length, the lens number is few.

3. big field angle.Sensor (sensor) that can adaptive many moneys polytypic has multimachine kind universality, field angle energy 〉=65 °;

4. low-cost.Promptly under the prerequisite that guarantees picture element, use cheap material to substitute expensive material as far as possible.Adopt the processing technology of easier realization;

Summary of the invention

Technical matters to be solved by this invention is to overcome the deficiencies in the prior art, provides a kind of image quality good and optical lens cheaply.

Technical matters of the present invention is solved by following technical scheme:

A kind of optical lens comprises first and second lens about the arranged in co-axial alignment of symmetrical; Described first lens have positive diopter, comprise the first surface and the second surface that are all convex surface, and described first surface is towards object plane, and the optics effective diameter of described first surface is less than second surface; Described second lens have negative diopter, comprise the 3rd surface and the 4th surface, and described the 3rd surface is the concave surface towards object plane, and described the 4th surface is a convex surface; The dispersion values of described first lens is greater than second lens, and the refractive index value of described first lens is less than second lens.

Preferably,

Also comprise and be positioned at the preceding fixed aperture of first lens near object space.

Described optical lens satisfies following relational expression:

1.25＜f/L＜1.55；

0.35＜f1/f＜0.55；

L _H/L＞0.25；

1＜n2/n1＜1.2；

1＜v1/v2＜3；

Wherein: f is the effective focal length value of described optical lens, and f1 is the effective focal length value of first lens, and L is the distance of the diaphragm of optical lens to imaging surface, L _HThe 4th surface is to the distance of imaging surface during for the air scaled distance, and n1 is the refractive index of first lens, and v1 is the dispersion values of first lens; N2 is the refractive index of second lens, and v2 is the dispersion values of second lens.

Also comprise the optical filter between second lens and imaging surface, described optical filter is a sheet glass, comprise first parallel-plate face adjacent and the second parallel-plate face adjacent, the coating surface one deck IR-cut filter membrane of at least one in described first and second parallel-plate face with imaging surface with second lens.

It is aspheric surface that described first and second lens at least all have a surface, and the coordinate figure of each point all satisfies following aspheric surface formula on the described non-spherical surface:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="cr"\; filenames="H2007100730076E00011.png,H2007100730076E00012.png"\; state="\{\{state\}\}">cr</figure-callout>}}^2}{1+\sqrt{1-(1+k)c^2{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="H2007100730076E00011.png,H2007100730076E00012.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}+a_2{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="H2007100730076E00011.png,H2007100730076E00012.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+a_4{\mathrm{<figure-callout\; id="4"\; label="r"\; filenames="H2007100730076E00012.png,H2007100730076E00021.png"\; state="\{\{state\}\}">r</figure-callout>}}^4+a_6{\mathrm{<figure-callout\; id="6"\; label="r"\; filenames="H2007100730076E00012.png,H2007100730076E00021.png"\; state="\{\{state\}\}">r</figure-callout>}}^6+a_8{\mathrm{<figure-callout\; id="8"\; label="r"\; filenames="H2007100730076E00041.png,H2007100730076E00071.png"\; state="\{\{state\}\}">r</figure-callout>}}^8+a_{10}{\mathrm{<figure-callout\; id="10"\; label="r"\; filenames="H2007100730076E00041.png"\; state="\{\{state\}\}">r</figure-callout>}}^{10}+a_{12}{\mathrm{<figure-callout\; id="12"\; label="r"\; filenames="H2007100730076E00011.png"\; state="\{\{state\}\}">r</figure-callout>}}^{12}$

Wherein: z is a starting point for the intersection point with each aspheric surface and optical axis, the axial axial value of vertical light, and k is the quadric surface coefficient, and c is the minute surface curvature of centre, and r is the minute surface centre-height; A2, a4, a6, a8, a10, a12 are asphericity coefficient.

The span of described quadric surface coefficient is :-15＜quadric surface coefficient＜15, the span of described minute surface curvature of centre is :-10＜minute surface curvature of centre＜10.

The material of described first lens and second lens is plastics or glass.

The parameter of described optical lens is as follows:

Lens parameters:

Asphericity coefficient:

Type	k	a2	a4	a6	a8	a10	a12
								First surface	-0.404	0.629	-0.195	0.189	-17.687	153.115	-620.158
Second surface	-0.254	-0.468	0.243	0.154	-6.836	13.900	-6.259
								The 3rd surface	9.295	-1.713	2.173	7.837	-77.002	203.807	-175.915
The 4th surface	-0.343	-1.276	0.494	3.510	-11.938	15.445	-7.043

The parameter of described optical lens is as follows:

Lens parameters:

Asphericity coefficient:

Type	k	a2	a4	a6	a8	a10	a12
								First surface	-1.929	0	-0.915	-72.978	3194.712	-4.861E+004	0
Second surface	-0.714	0	0.684	-31.631	231.757	-809.043	0
								The 3rd surface	-1.177	0	-2.533	-18.474	412.024	-2179.793	0
The 4th surface	0	0	1.335	4.260	-6.458	37.748	0

The parameter of described optical lens is as follows:

Lens parameters:

Asphericity coefficient:

Type	k	a2	a4	a6	a8	a10	a12
								First surface	-2.816	0	-0.755	-30.097	956.209	-1.268E+004	0
Second surface	-0.807	0	0.561	-23.077	134.704	-445.707	0
								The 3rd surface	-6.890	0	2.890	-0.293	-32.206	644.018	0
The 4th surface	0	0	1.194	2.983	-11.692	29.919	0

The beneficial effect that the present invention is compared with the prior art is:

First lens of optical lens of the present invention have positive light coke, can effectively gather light, and first lens adopt the material dispersion values big, can effectively subdue aberration; The second lens integral body bends towards object plane, and wherein the 3rd of second lens the surperficial face shape face shape of second surface of first lens of fitting makes light on the 3rd surface less incident angle be arranged, and can effectively control the senior aberration of whole optical lens; The 4th surface of second lens is a convex surface, slightly has heaving of the sea trend, can effectively reduce the chief ray emergence angle of edge, improves image planes edge illumination.And the present invention only adopts two lens, makes optical lens of the present invention guarantee that image quality reduces cost in good.

The diaphragm of optical lens of the present invention places the forefront near object plane, can make optical lens simple in structure, compact, and length overall is little.The total length of this lens optical camera lens, and have big field angle makes it can adapt to multiple sensors such as 1/7,1/7.5,1/8, satisfies the needs of multiple mobile phone.

Optical lens of the present invention can effectively be subdued various aberrations, comprises spherical aberration, coma, astigmatism, the curvature of field and distortion etc., has promoted relative exposure.

Optical lens focal length of the present invention is lacked but is had long back Jiao simultaneously, greatly facilitates production, can effectively improve yield, reduces production costs, and is applicable to large-scale industrial production.

The present invention has controlled incident angle＜28 of light on every °, has eliminated the ghost phenomenon to a certain extent.

Lens of the present invention can adopt plastic material, thereby greatly reduce production cost, are applicable to large-scale industrial production.

Description of drawings

Fig. 1 is the structural representation of the specific embodiment of the invention one

Fig. 2 is the MTF figure of the specific embodiment of the invention one;

Fig. 3 is the conforming synoptic diagram in the visual field of the specific embodiment of the invention one;

Fig. 4 is the transverse axis aberration synoptic diagram of the specific embodiment of the invention one;

Fig. 5 is the distortion synoptic diagram of the optical lens of the specific embodiment of the invention one;

Fig. 6 is the structural representation of the specific embodiment of the invention two

Fig. 7 is the MTF figure of the specific embodiment of the invention two;

Fig. 8 is the conforming synoptic diagram in the visual field of the specific embodiment of the invention two;

Fig. 9 is the transverse axis aberration synoptic diagram of the specific embodiment of the invention two;

Figure 10 is the distortion synoptic diagram of the specific embodiment of the invention two;

Figure 11 is the structural representation of the specific embodiment of the invention three

Figure 12 is the MTF figure of the specific embodiment of the invention three;

Figure 13 is the conforming synoptic diagram in the visual field of the specific embodiment of the invention three;

Figure 14 is the transverse axis aberration synoptic diagram of the specific embodiment of the invention three;

Figure 15 is the distortion synoptic diagram of the specific embodiment of the invention three.

Embodiment

Optical lens shown in Fig. 1,6,11 comprises the first coaxial lens 1 and second lens 2 successively from object space; First lens 1 and second lens 2 are respectively about symmetrical.Described first lens 1 have positive diopter, comprise first surface 11 and second surface 12; Described second lens 2 have negative diopter, comprise the 21 and the 4th surface 22, the 3rd surface.First surface 11 and second surface 12 are all convex surface, and the optics effective diameter of described first surface 11 is less than second surface 12.Described the 3rd surface 21 is the concave surface towards object plane, and described the 4th surface 22 is a convex surface.

It is aspheric surface that first lens 1 and second lens 2 all have a surface at least, and the coordinate figure of each point all satisfies following aspheric surface formula on this non-spherical surface:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="cr"\; filenames="H2007100730076E00011.png,H2007100730076E00012.png"\; state="\{\{state\}\}">cr</figure-callout>}}^2}{1+\sqrt{1-(1+k)c^2{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="H2007100730076E00011.png,H2007100730076E00012.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}+a_2{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="H2007100730076E00011.png,H2007100730076E00012.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+a_4{\mathrm{<figure-callout\; id="4"\; label="r"\; filenames="H2007100730076E00012.png,H2007100730076E00021.png"\; state="\{\{state\}\}">r</figure-callout>}}^4+a_6{\mathrm{<figure-callout\; id="6"\; label="r"\; filenames="H2007100730076E00012.png,H2007100730076E00021.png"\; state="\{\{state\}\}">r</figure-callout>}}^6+a_8{\mathrm{<figure-callout\; id="8"\; label="r"\; filenames="H2007100730076E00041.png,H2007100730076E00071.png"\; state="\{\{state\}\}">r</figure-callout>}}^8+a_{10}{\mathrm{<figure-callout\; id="10"\; label="r"\; filenames="H2007100730076E00041.png"\; state="\{\{state\}\}">r</figure-callout>}}^{10}+a_{12}{\mathrm{<figure-callout\; id="12"\; label="r"\; filenames="H2007100730076E00011.png"\; state="\{\{state\}\}">r</figure-callout>}}^{12}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;$

Wherein: z is for being starting point with each aspheric surface and optical axis o intersection point, the axial value of vertical optical axis o direction, i.e. and minute surface depth value is because of selected lens shape is the axisymmetric lens, so this aspheric surface formula is all got the even item.K is the quadric surface coefficient, i.e. the tapering of lens; C is the minute surface curvature of centre, c=1/R, and wherein R is a minute surface curvature of centre radius; R is the minute surface centre-height; A2, a4, a6, a8, a10, a12 are asphericity coefficient.Can determine the shape that each is surperficial by above aspheric surface formula.

The span of described quadric surface coefficient k is :-15＜k＜15, the span of described minute surface curvature of centre c is :-10＜c＜10, the span of described asphericity coefficient a2, a4, a6, a8, a10, a12 can be arbitrary value.

This optical lens also can comprise the fixed aperture 4 that is positioned at first lens, 1 preceding close object space, and described fixed aperture 4 has the fixedly aperture of bore.This optical lens also can comprise and is positioned at the optical filters 3 of second lens 2 back away from object space.This optical filter 3 is a sheet glass, comprises and the first parallel-plate face 31 and the second parallel-plate face 32.The described first parallel-plate face 31 is adjacent with second lens 2, and the described second parallel-plate face 32 is adjacent with imaging surface.

Above-mentioned optical lens meets the following conditions:

1.25＜f/L＜1.55；

0.35＜f1/f＜0.55；

L _H/L＞0.25；

1＜n2/n1＜1.2；

1＜v1/v2＜3；

Wherein: f is the effective focal length value of whole optical lens; F1 is the effective focal length value of first lens 1; L is the optical lens length overall, and promptly the diaphragm of optical lens is to the distance of imaging surface; L _HBe coke number behind the camera lens, promptly during the air scaled distance the 4th of optical lens the surface to the distance of imaging surface.The air scaled distance is meant that hypothesis does not have the situation of glass filter; N1 is the refractive index of first lens 1, and v1 is the dispersion values of first lens 1; N2 is the refractive index of second lens 2, and v2 is the dispersion values of second lens 2.

Satisfy the optical lens of above-mentioned condition and can on the basis of shortening the camera lens length overall, guarantee suitable back focal length, can also each aberration be that non-point image difference and aberrance are well corrected especially, and obtain desirable optical property.

Described first lens, 1 the most close diaphragm should be chosen high dispersion values material, color difference eliminating influence as far as possible; The trend of described second lens 2 control light to the imaging surface should be chosen high-index material for shortening the optical lens length overall.Difference in size between first lens 1 and 2 refractive indexes of second lens and the dispersion values then helps the elimination of other various aberrations simultaneously.Therefore first lens 1 of above-mentioned optical lens are preferably high chromatic dispersion low-index material, and second lens 2 are preferably the high-refractivity and low-dispersion material.

Because well-formed disclosed by the invention can select the optics material for use in broad range.Be embodied in first lens 1 and second lens 2 all can adopt structural plastic material or glass structure material.

The optical filter 3 preferred scorching glass material of the borosilicic acid of making by the fusion virgin material, refractive index n 4=1.5168, the chromatic dispersion v4=64.17 of using.Preferably, the coating surface one deck IR-cut filter membrane (IR-cutCoating) of at least one in the first parallel-plate face 31 of described optical filter 3 and the second parallel-plate face 32, come from Infrared in the object reflection ray with filtering, thereby improve image quality.

Embodiment one, two, three has provided the concrete parameter value of the embodiment that constitutes based on said structure.Wherein, radius-of-curvature is meant the radius-of-curvature of the curved surface of each face and optical axis intersection; The distance value is meant by object plane and is oriented to the distance of image planes from a certain selected face to the following one side that is adjacent along optical axis.The unit of these concrete parameters all is a millimeter (mm).

Embodiment one:

Optical lens shown in Figure 1 is the optical lens of embodiment one, and the parameter of this optical lens is as follows:

Lens parameters:

Asphericity coefficient:

Type	k	a2	a4	a6	a8	a10	a12
								First surface	-0.404	0.629	-0.195	0.189	-17.687	153.115	-620.158
Second surface	-0.254	-0.468	0.243	0.154	-6.836	13.900	-6.259

Type	k	a2	a4	a6	a8	a10	a12
								The 3rd surface	9.295	-1.713	2.173	7.837	-77.002	203.807	-175.915
The 4th surface	-0.343	-1.276	0.494	3.510	-11.938	15.445	-7.043

For the optical lens of embodiment one, its optical property figure sees Fig. 2,3,4,5.

Fig. 2 is the lens optical modulation transfer function curve (MTF) of optical lens, transverse axis representation space frequency among the figure, and unit: line is to every millimeter (lp/mm); The longitudinal axis is represented the numerical value of modulation transfer function (MTF), and the numerical value of described MTF is used for estimating the image quality of camera lens, and span is 0-1, and the image quality of the high more straight more expression camera lens of MTF curve is good more, and is strong more to the reducing power of true picture.Imaging situation during the desirable camera lens optimal imaging of the diffraction limit among Fig. 2 (DIFF LIMIT) representative.This is a kind of limiting case, and the actual camera lens that uses is the effect that impossible reach such.Actual MTF curve and its DIFF LIMIT curve are approaching more, represent that its image quality is good more.S among Fig. 2 and T represent the MTF curve on sagitta of arc direction and the meridian direction (two mutually perpendicular faces) respectively.DEG is angle (degree), has represented the numerical value of each field angle.In the image quality of research camera lens, can choose 0 visual field usually, 0.3 visual field; 0.5 the visual field, 0.7 visual field, several representative visual fields such as 1 visual field are as research object; come the picture element of overall evaluation camera lens, wherein the 0--0.7 visual field is considered to most important usually.For example, the field angle of a camera lens is 60 degree, then its angle of half field-of view is that 30 degree are (because camera lens of the present invention all is the optical texture along symmetrical, often only study the optical property of one half field-of-view in the analysis software, promptly there is angle of half field-of view one to say), then its 0.3 visual field is 9 degree, and 0.5 visual field is 15 degree, and 0.7 visual field is 21 degree.And can the visual field of setting be adjusted according to the concrete condition of design in the concrete operations, in Fig. 2, selected several visual fields just are 0 degree, 9.3 degree, and 15.5 degree, 21.7 degree, 25.5 degree come overall evaluation the design's picture element.Can see, among the figure MTF curve of each visual field and meridian direction (T) and sagitta of arc direction (S) direction very close to.This image quality of camera lens that is just embodying this embodiment is outstanding, it shows: camera lens is in each visual field, the imaging performance of meridian direction (T) and this both direction of sagitta of arc direction (S) has good consistance, can guarantee that in other words camera lens can both blur-free imaging on whole imaging surface.And clear in the middle of can not occurring, the situation that the edge is just fuzzy.

Fig. 3 is the conforming synoptic diagram in the visual field of this embodiment, wherein transverse axis is represented distance, 0 place is the ideal image face, the position of the optimal imaging face when designing exactly, and in actual the manufacturing, can not accomplish to have no error, the sensor that is often used for accepting being translated into behind the light digital signal generally all is placed on imaging surface position (sensor) and can just in time be placed on the place of optimal imaging face, but some deviations are arranged.S and T represent the MTF curve on sagitta of arc direction and the meridian direction (two mutually perpendicular two faces) respectively.DEG is angle (degree), has represented the numerical value of each field angle.It has been generally acknowledged that MTF numerical value then thinking more than 0.3 and can accept, i.e. the distinguishable limiting case of human eye.Fig. 3 has reflected a situation of image planes out of focus, and as can be seen from Figure 3, it is higher to represent the MTF of each visual field (direction) to take parameter on trendline, even imaging surface departs from certain distance still can be guaranteed＞=0.3.。This depth of focus of camera lens that shows this embodiment is longer, the needs that are suitable for producing.

Fig. 4 is the transverse axis aberration synoptic diagram of this embodiment, maximum field of view angle in Fig. 4 (MAXIUM FIELD), be that angle of half field-of view is 34.5 degree, whole field angle is 69 degree, transverse axis among the figure is a length scale, the um of unit (1*E-6m), Aili spot (Airy), promptly under the situation of diffraction limit (the optimal imaging situation of desirable camera lens), minimum hot spot is an Aili spot during light focusing.As can be seen from Figure, all in the Aili spot magnitude range, the chromatic aberration correction of expression camera lens is good for the size of transverse axis aberration.

Fig. 5 is the distortion synoptic diagram of the optical lens of this embodiment, and wherein transverse axis is a number percent, and the longitudinal axis is the visual field.Distortion is a kind of distortion of real lens during to object image-forming, and it can make straight line be imaged as curve, is inevitable in actual imaging.Three curves among Fig. 5 are represented the visible light (being used for representing the distortion situation in the whole visible-range) of three kinds of colors respectively, its in whole visual field distortion value all between-2%-2%, and the distortion in this scope belongs to the insensitive category of human eye, and practicality can not influence imaging constantly yet.

Embodiment two:

Optical lens shown in Figure 6 is the optical lens of embodiment two, and the parameter of this optical lens is as follows:

Lens parameters:

Type	Radius-of-curvature (R)	Apart from value (d)	Refractive index	Dispersion values
					The diaphragm face		0
First surface	1.013	0.586	1.53	55.6
					Second surface	-0.336	0.123
The 3rd surface	-0.213	0.382	1.585	29.5
					The 4th surface	-0.550	0.400
The first parallel-plate face		0.300	1.5168	64.17

Asphericity coefficient:

Type	k	a2	a4	a6	a8	a10	a12
								First surface	-1.929	0	-0.915	-72.978	3194.712	-4.861E+004	0
Second surface	-0.714	0	0.684	-31.631	231.757	-809.043	0
								The 3rd surface	-1.177	0	-2.533	-18.474	412.024	-2179.793	0
The 4th surface	0	0	1.335	4.260	-6.458	37.748	0

For the optical lens of embodiment two, its optical property figure sees Fig. 7,8,9,10.Fig. 7 is the lens optical modulation transfer function curve (MTF) of optical lens, each line is illustrated in the meridian visual field (T) of different visual fields and each visual field and the MTF of sagitta of arc visual field (S) among the figure, camera lens is in each visual field as we know from the figure, the imaging performance of meridian visual field (T) and sagitta of arc visual field (S) both direction has good consistance, can guarantee that camera lens can both blur-free imaging on whole imaging surface.And situation clear in the middle of can not occurring, that the edge is just fuzzy.The depth of focus that shows camera lens as can be seen from Figure 8 is longer, the needs that are suitable for producing.All in the Aili spot magnitude range, the chromatic aberration correction of expression camera lens is good for the size of transverse axis aberration as can be seen from Figure 9.As can be seen from Figure 10, distortion value is all between-2%-2% in whole visual field, and the distortion in this scope belongs to the insensitive category of human eye, also can not influence imaging during use.

Embodiment three:

Optical lens shown in Figure 11 is the optical lens of embodiment two, and the parameter of this optical lens is as follows:

Lens parameters:

Asphericity coefficient:

Type	k	a2	a4	a6	a8	a10	a12
								First surface	-2.816	0	-0.755	-30.097	956.209	-1.268E+004	0
Second surface	-0.807	0	0.561	-23.077	134.704	-445.707	0
								The 3rd surface	-6.890	0	2.890	-0.293	-32.206	644.018	0
The 4th surface	0	0	1.194	2.983	-11.692	29.919	0

For the optical lens of embodiment three, its optical property figure sees Figure 12,13,14,15.Figure 12 is the lens optical modulation transfer function curve (MTF) of optical lens, each line is illustrated in the meridian visual field (T) of different visual fields and each visual field and the MTF of sagitta of arc visual field (S) among the figure, camera lens is in each visual field as we know from the figure, the imaging performance of meridian visual field (T) and sagitta of arc visual field (S) both direction has good consistance, guarantees that camera lens can both blur-free imaging on whole imaging surface.And clear in the middle of can not occurring, the situation that the edge is just fuzzy.The optical lens depth of focus of this embodiment is longer as can be seen from Figure 13, the needs that are suitable for producing.All in the Aili spot magnitude range, the chromatic aberration correction of expression camera lens is good for the size of transverse axis aberration as can be seen from Figure 14.As can be seen from Figure 15, distortion value is all between-2%-2% in whole visual field, and the distortion in this scope belongs to the insensitive category of human eye, also can not influence imaging during use.

Above content be in conjunction with concrete preferred implementation to further describing that the present invention did, can not assert that concrete enforcement of the present invention is confined to these explanations.For the general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace, all should be considered as belonging to protection scope of the present invention.

Claims (8)

1. optical lens, comprise about symmetrical and from the object plane to the imaging surface fixed aperture of arranged in co-axial alignment, first lens and second lens successively; Described first lens have positive diopter, comprise the first surface and the second surface that are all convex surface, and described first surface is towards object plane, and the optics effective diameter of described first surface is less than second surface; Described second lens have negative diopter, comprise the 3rd surface and the 4th surface, and described the 3rd surface is the concave surface towards object plane, and described the 4th surface is a convex surface; The dispersion values of described first lens is greater than second lens, and the refractive index value of described first lens is characterized in that less than second lens:

Described optical lens satisfies following relational expression:

1.25＜f/L＜1.55；

0.35＜f1/f＜0.55；

L _H/L＞0.25；

1＜n2/n1＜1.2；

1＜v1/v2＜3；

Wherein: f is the effective focal length value of described optical lens, and f1 is the effective focal length value of first lens, and L is the distance of the diaphragm of optical lens to imaging surface, L _HThe 4th surface is to the distance of imaging surface during for the air scaled distance, and n1 is the refractive index of first lens, and v1 is the dispersion values of first lens; N2 is the refractive index of second lens, and v2 is the dispersion values of second lens.

2. optical lens according to claim 1 is characterized in that:

Also comprise the optical filter between second lens and imaging surface, described optical filter is a sheet glass, comprise first parallel-plate face adjacent and the second parallel-plate face adjacent, the coating surface one deck IR-cut filter membrane of at least one in described first and second parallel-plate face with imaging surface with second lens.

3. optical lens according to claim 1 and 2 is characterized in that:

It is aspheric surface that described first and second lens all have a surface at least, and the coordinate figure of each point all satisfies following aspheric surface formula on the described non-spherical surface:

$z=\frac{{\mathrm{cr}}^2}{1+\sqrt{1-(1+k)c^2{r}^2}}+a_2{r}^2+{a_{4}r}^4+a_6{r}^6+a_8{r}^8+a_{10}{r}^{10}+a_{12}{r}^{12}$

Wherein: z is a starting point for the intersection point with each aspheric surface and optical axis, the axial axial value of vertical light, and k is the quadric surface coefficient, and c is the minute surface curvature of centre, and r is the minute surface centre-height; A2, a4, a6, a8, a10, a12 are asphericity coefficient.

4. optical lens according to claim 3 is characterized in that:

The span of described quadric surface coefficient is :-15＜quadric surface coefficient＜15, the span of described minute surface curvature of centre is :-10＜minute surface curvature of centre＜10.

5. optical lens according to claim 4 is characterized in that:

The material of described first lens and second lens is plastics or glass.

6. optical lens according to claim 5 is characterized in that:

The parameter of described optical lens is as follows:

Lens parameters:

Asphericity coefficient:

Type k a2 a4 a6 a8 a10 a12 First surface -0.404 0.629 -0.195 0.189 -17.687 153.115 -620.158 Second surface -0.254 -0.468 0.243 0.154 -6.836 13.900 -6.259 The 3rd surface 9.295 -1.713 2.173 7.837 -77.002 203.807 -175.915 The 4th surface -0.343 -1.276 0.494 3.510 -11.938 15.445 -7.043 。

7. optical lens according to claim 5 is characterized in that:

The parameter of described optical lens is as follows:

Lens parameters:

Asphericity coefficient:

Type k a2 a4 a6 a8 a10 a12 First surface -1.929 0 -0.915 -72.978 3194.712 -4.861E+004 0 Second surface -0.714 0 0.684 -31.631 231.757 -809.043 0 The 3rd surface -1.177 0 -2.533 -18.474 412.024 -2179.793 0 The 4th surface 0 0 1.335 4.260 -6.458 37.748 0 。

8. optical lens according to claim 5 is characterized in that:

The parameter of described optical lens is as follows:

Lens parameters:

Asphericity coefficient:

Type k a2 a4 a6 a8 a10 a12 First surface -2.816 0 -0.755 -30.097 956.209 -1.268E+004 0 Second surface -0.807 0 0.561 -23.077 134.704 -445.707 0 The 3rd surface -6.890 0 2.890 -0.293 -32.206 644.018 0 The 4th surface 0 0 1.194 2.983 -11.692 29.919 0 。

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