CN101210996A - Minsize pick-up lens - Google Patents

Abstract

A micro taking lens can be applied for image retrieving products, comprising a first lens with minus diopter, a free-form surface prism with plus diopter and a second lens with plus diopter, which are arranged from the object space to the imaging space, wherein, the free-form surface prism comprises an incident plane, a reflection plane and an emergent plane. The first lens is arranged on one side of the incident plane, the second lens is arranged on one side of the emergent plane. The free-form surface prism has the same effect of adding non-spherical surface coefficient on the surface of one rectangular prism.

Description

Minisize image acquisition lens

Technical field

The present invention relates to a kind of sampling image lens, particularly about a kind of minisize image acquisition lens that is applicable to image capture unit.

Background technology

The integration of image capture unit and photoelectric technology has become the trend of current development in science and technology, in order to satisfy portable requirement, light, thin, short, the little primary demand that has become image capture unit.On the eyeglass form and selection of sampling image lens, because the selection of traditional sphere abrading glass eyeglass is more, and comparatively favourable for correcting chromatic aberration, widely industry is used.Yet when sphere abrading glass eyeglass was used in less and visual angle (Wide-angle) the bigger situation of numerical aperture (F Number), the correction of aberrations such as spherical aberration and astigmatism is difficulty still.The appearance of aspheric mirror has solved the problems referred to above, be applied in the optical system of camera lens, can significantly improve image quality, reduce the barrel distortion of wide-angle lens, and the alternative several spherical lens aberration for compensation of a slice non-spherical lens, can simplify the optical design of camera lens quite significantly, reduce volume and weight.Yet, the traditional glass camera lens still must use a plurality of eyeglasses could correct with great visual angle off-axis aberration and the problem of aberration, the camera lens overall dimensions is long, volume is big, cost is higher thereby cause, and the processing of aspheric surface glass mirror is difficult for, and can be subjected to certain restriction in the time of therefore on being used in the light and thin type digital product.Comparatively speaking, the aspheric surface glass lens is more easily processed, cost is lower, and therefore, industry adopts the optical element of aspheric surface glass lens as the small image extraction camera lens more, to shorten whole optical system.

With regard to the design of wide-angle lens, the design factor that needs to consider comprises off-axis aberration and the aberration that must correct with great visual angle, and severe distortion etc., therefore design is more difficult, problems such as finally easily cause the shape of eyeglass to be difficult to process or main beam incident angle (Chief Ray Angle) is too big.Though many designs of wide-angle lens have been exposed in U.S. Patent number 4493537,5251073,4525038 etc., can be under very short total length, overcome various optical aberrations and take into account the design of problems such as actual processing extremely rare.Therefore, also there is preceding case to propose to utilize the form of periscopic or free form surface (Free-Form Surface) prism to realize the purpose of compression stroke, as U.S. Patent number 6323892 etc.Yet periscopic design only can realize purpose with the light path turnover, the function of not correcting aberration by a catoptron.

The employing free curved surface prism has the following advantages: light path is repeatedly reflection in prism, can make total system shorten because of folding (Folding) effect; Reflecting surface can not produce aberration (Chromatic Aberration), so total system can be because of a large amount of aberration that traditional refractor produced, and needs other eyeglass to do compensation (Compensation), so the element number of total system is few; Therefore optical surface is easier to stablize when system assembles because prism concerns that its relative position is fixed.Yet the free curved surface prism structure that existing sampling image lens adopts is comparatively complicated mostly, and therefore design, processing, fixing all difficulties comparatively still have necessity of further improvement.

Summary of the invention

Fundamental purpose of the present invention is to provide a kind of minisize image acquisition lens, and it adopts a free curved surface prism, by the purpose that the incident beam reflection can be realized shortening the optics length overall.

Another object of the present invention is to provide a kind of minisize image acquisition lens, it is simple in structure, handling ease, cost are lower, has with great visual angle and have good image quality.

For achieving the above object, the invention provides a kind of minisize image acquisition lens, can be applicable on the image capture unit, this sampling image lens comprises the prism of negative dioptric first lens, positive diopter from the object side to the image side successively, and second lens of positive diopter, wherein this prism comprises a plane of incidence, a reflecting surface and an exit facet, and first lens are arranged at a side of the plane of incidence and the side that second lens are arranged at exit facet.First lens are a biconcave lens, comprise that one is depression first of configuration and also is second of depression configuration with respect to imaging surface with respect to subject.This prism is a free curved surface prism, is equivalent to the attached asphericity coefficient that gives on a right-angle prism face.Second of relative first lens of the plane of incidence of this prism and establish, the relative inclined light shaft setting of reflecting surface, and exit facet is established towards imaging surface, wherein the plane of incidence, exit facet are convex surface, and reflecting surface is a plane, also can be a curved surface.These second lens are arranged between free curved surface prism and the imaging surface, and its two surface can be the biconvex form, also can be concavo-convex form.Further be provided with an aperture diaphragm between these second lens and the free curved surface prism.

Have at least one side to be aspheric surface in first, second face of first lens; The plane of incidence and the exit facet of prism are aspheric surface; Second lens also can be designed to a non-spherical lens.

First lens, prism and second lens are made by plastics, and second lens can be made by glass.

First lens of minisize image acquisition lens of the present invention, prism and second lens meet the following conditions:

1.3＜|f1/f|＜2.3；

2.5＜f2/f＜5.0；

2.5＜f3/f＜4.0；

Wherein, f is the whole effective focal length (Effective Focal Length) of system, and f1 is the effective focal length of first lens, and f2 is the effective focal length of prism, and f3 is the effective focal length of second lens.

Compared with prior art, camera lens of the present invention only is made up of two lens and a prism, has that framework is succinct, easy to assembly, the visual angle is big, volume is little, lightweight advantage; By a free curved surface prism, optical axis can be folded to 90 degree, make light path produce turnover, thereby shorten the front and back length and the reduced volume of camera lens, rectifiable various aberrations obtain the good picture of separating simultaneously; Adopt the glass lens of ejection formation and add aspheric surface,, can significantly reduce cost, and be easy to aberration correction, shorten the optics length overall of camera lens and improve yield to replace traditional glass mirror.

The present invention is further illustrated below in conjunction with accompanying drawing and embodiment.

Description of drawings

Fig. 1 is the optical structure chart of minisize image acquisition lens of the present invention.

Fig. 2 is the optical structure chart of minisize image acquisition lens of the present invention according to numerical value embodiment one.

Fig. 3 to Fig. 6 is respectively the performance figure of longitudinal spherical aberration, the curvature of field, distortion and the lateral chromatic aberration of numerical value embodiment one of the present invention.

Fig. 7 is the optical structure chart of minisize image acquisition lens of the present invention according to numerical value embodiment two.

Fig. 8 to Figure 11 is respectively the performance figure of longitudinal spherical aberration, the curvature of field, distortion and the lateral chromatic aberration of numerical value embodiment two of the present invention.

Figure 12 is the optical structure chart of minisize image acquisition lens of the present invention according to numerical value embodiment three.

Figure 13 to Figure 16 is respectively the performance figure of longitudinal spherical aberration, the curvature of field, distortion and the lateral chromatic aberration of numerical value embodiment three of the present invention.

Figure 17 is the optical structure chart of minisize image acquisition lens of the present invention according to numerical value embodiment four.

Figure 18 to Figure 21 is respectively the performance figure of longitudinal spherical aberration, the curvature of field, distortion and the lateral chromatic aberration of numerical value embodiment four of the present invention.

Embodiment

Relevant detailed description of the present invention and technology contents, existing as follows with regard to accompanying drawings:

Minisize image acquisition lens of the present invention can be applicable to image capture unit, is used for object is imaged in Image Sensor, as charge coupled cell (CCD) or complementary metal oxide semiconductor (CMOS) (CMOS).

Please refer to the composition framework of minisize image acquisition lens of the present invention shown in Figure 1, it comprises the prism 2 of negative dioptric first lens 1, positive diopter from the object side to the image side successively, and second lens 3 of positive diopter, wherein the prism 2 and first lens 1 are arranged side by side, and second lens 3 are positioned at prism 2 belows and contiguous picture side.After seeing through first lens 1, prism 2 and second lens 3 from the light of subject, focus on a CCD or the CMOS image sensor 4 (imaging surface), and obtain blur-free imaging.

First lens 1 are a biconcave lens, and its optical function is mainly collection light.These first lens 1 comprise that one is cave in first S1 of configuration and second S2 that also is the configuration that caves in respect to prism 2 with respect to subject, and have at least one side to be aspheric surface among first, second face S1, the S2, in order to correct distortion (Distortion) and lateral chromatic aberration (Lateral Color).

Prism 2 is a free curved surface prism (Free-FormS urface Prism), is equivalent to the attached asphericity coefficient that gives on a right-angle prism (Right Angle Prism) face.At this, though also can use the prism of on-right angle, consider processing stability and tolerance (Tolerance) tolerance, the right angle is preferable angle.Prism 2 can be realized multinomial optical function simultaneously, except that optical axis being turned to 90 degree, also provides three faces to be used for correcting aberration.This prism 2 comprises second S2 with first lens 1 is relative and establish plane of incidence S3, the reflecting surface S4 that is provided with of inclined light shaft relatively, and the exit facet S5 that establishes towards imaging surface 4, wherein plane of incidence S3, exit facet S5 are convex surface and are aspheric surface, and reflecting surface S4 is a plane, also can be a curved surface.First lens 1 are arranged at the side of plane of incidence S3, and second lens 3 are arranged at the side of exit facet S5.

Second lens 3 are arranged between free curved surface prism 2 and the imaging surface 4, and its two surperficial S6 and S7 are the biconvex form, also can be to be concavo-convex form.The main optical function of second lens 3 is for revising spherical aberration (S pherical Aberration) and axle is gone up aberration, and its preferred versions is for comprising at least one aspheric aspheric surface convex lens, but also can be a spherical convex lens.

Further be provided with an aperture diaphragm (Aperture Stop) 5 between second lens 3 and the free curved surface prism 2, in order to control light amount of incident.For obtaining imaging effect preferably, between aperture diaphragm 5 and imaging surface 4, further be provided with a glass plate (Glass Cover) 6, can plate and have certain effect the film of (for example: antireflection or infrared ray filter) on it.

As mentioned above, in the present invention, first lens 1, free curved surface prism 2 and second lens 3 all can adopt the aspheric surface design, but like this except compensate for chromatic aberration and rectification off-axis aberration, also can help to shorten the length overall of lens optical system, make the eyeglass number of camera lens reduce to minimum and weight reduction significantly.Preferably, first lens 1, prism 2 and second lens 3 are made by plastics, but second lens 3 also can be made by glass.

In the minisize image acquisition lens of the present invention, from the light beam of subject by behind first lens 1, be incident in the prism 2 and the face S4 of being reflected reflexes to exit facet S5 by the plane of incidence S3 of prism 2, penetrate to second lens 3 by aperture diaphragm 5 by exit facet S5 at last.The reflecting surface S4 of prism 2 can make the optical axis folding of the optical system of sampling image lens of the present invention turn 90 degrees to the internal reflection of light beam, can make the light path folding, therefore compares with dioptric system, and optical system itself is reduced.In addition, free curved surface prism 2 comprises plane of incidence S3 and the exit facet S5 as plane of refraction that is equivalent to three eyeglasses, and reflecting surface S4, compares with the catoptron that has only reflecting surface, and the degree of freedom of aberration correction is big.In addition, owing to be full of the transparent body higher, therefore design specific energy prolongation optical path length mutually, thereby make optical system slimming, miniaturization with being configured in airborne lens or catoptron etc. than the refractive index of air in prism 2 inside.

For realizing preferable optical property, first lens 1 of sampling image lens of the present invention, prism 2 and second lens 3 need meet the following conditions:

1.3＜|f1/f|＜2.3 (1)

Wherein, f is the whole effective focal length (Effective Focal Length) of system, and f1 is the effective focal length of first lens 1.When | f1/f| prescribes a time limit greater than last, astigmatism (Astigmatism) undercorrection, and less than down in limited time, it is big that longitudinal chromatic aberration (Axiai Color) becomes.In addition,

2.5＜f2/f＜5.0 (2)

Wherein, f is the whole effective focal length of system, and f2 is the effective focal length of prism 2.In limited time it is big that lateral chromatic aberration (Lateral Color) becomes greater than last as f2/f, and less than down in limited time, spherical aberration (Spherical Aberration) and coma (Coma) are difficult to correct.In addition,

2.5＜f3/f＜4.0 (3)

Wherein, f is the whole effective focal length of system, and f3 is the effective focal length of second lens 3.In limited time promptly the focal length of second lens 3 is oversize, can cause total system elongated gradually greater than last as f3/f, and less than down in limited time, coma (Coma) and astigmatism (Astigmatism) are difficult to correct.

Concrete numerical value embodiment below with reference to caption minisize image acquisition lens of the present invention.

Numerical value embodiment one

As shown in Figure 2, the embodiment one of minisize image acquisition lens of the present invention comprises free curved surface prism 21, an aperture diaphragm 51 of negative dioptric first lens 11, a positive diopter, second lens 31, a glass plate 61 and an imaging surface 41 of a positive diopter.First lens 11 are a biconcave lens.The plane of incidence S31 and the exit facet S51 of free curved surface prism 21 are convex surface, and reflecting surface S41 is a plane.Second lens 31 are a biconvex lens.The concrete numerical value such as the following table of each element are listed:

The surface sequence number	Radius-of-curvature (mm) (Radius of Curvature)	Distance/thickness (mm) (Distance/Thickness)	Refractive index (Nd)	Abbe number (Vd)
					S0		∞
S11	-3.740	1.1	1.5136	57.4
					S21	1.90	1.70
S31	4.048	2.726	1.5136	57.4
					S41	∞	-2.726	1.5136	57.4
S51	2.692	-1.5
					S61	∞	-0.1
S71	-2.491	-0.7	1.536	57.4
					S81	18.681	-1.77
S91	∞	-0.8	1.51633	64.1
					S101	∞

Illustrate: in last table,, therefore negative spacing is arranged because of rotated 90 degree in the reflecting surface S41 place of prism 21 coordinate system.

In numerical value embodiment one, first lens 11, prism 21 and second lens 31 are aspheric mirror, satisfy following aspheric surface formula:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="ch"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">ch</figure-callout>}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{<figure-callout\; id="4"\; label="Ah"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">Ah</figure-callout>}}^4+{\mathrm{<figure-callout\; id="6"\; label="Bh"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">Bh</figure-callout>}}^6+{\mathrm{Ch}}^8+{\mathrm{Dh}}^{10}$

Wherein, z be along optical axis direction highly for the position of h with the surface vertices shift value apart from optical axis for referencial use, k is the tapering constant, c represents the inverse of radius-of-curvature, h represents the eyeglass height, A, B, C, D is asphericity coefficient, A represents quadravalence asphericity coefficient (4th OrderAspherical Coefficient), B represents six rank asphericity coefficients (6th OrderAspherical Coefficient), C represents eight rank asphericity coefficients (8th OrderAspherical Coefficient), and D represents ten rank asphericity coefficients (10th OrderAsphe rical Coefficient).

Particularly, two surperficial S11, the S21 of first lens 11, the plane of incidence S31 and the exit facet S51 of prism 21, and the surperficial S71 of second lens 31 is aspheric surface, its aspheric correlation values is listed in the table below successively:

The correlated performance index such as the following table of the minisize image acquisition lens of implementing according to numerical value embodiment one:

Whole effective focal length (f)	1.3mm
		Field of View(F.O.V)	120degree
Total Length of Lens System	13.13mm
		F-number	2.82
|f1/f|	1.77
		f2/f	3.34
f3/f	3.33

As seen from the above table, the focal length ratio that is limited to (3) by relational expression (1) | f1/f| is 1.77, and f2/f is 3.34, and f3/f is 3.33, all is positioned at desired bound scope.

Fig. 3 to Fig. 6 has shown longitudinal spherical aberration (Longitudinal Spherical Aberration), the curvature of field (Field Sags), distortion (Distortion) and lateral chromatic aberration (Lateral Color) curve map of the camera lens of numerical value embodiment one of the present invention respectively, shows that the camera lens of numerical value embodiment one of the present invention has preferable optical appearance.

Numerical value embodiment two

As shown in Figure 7, the embodiment two of minisize image acquisition lens of the present invention comprises free curved surface prism 22, an aperture diaphragm 52 of negative dioptric first lens 12, a positive diopter, second lens 32, a glass plate 62 and an imaging surface 42 of a positive diopter.First lens 12 are a biconcave lens.The plane of incidence S32 and the exit facet S52 of free curved surface prism 22 are convex surface, and reflecting surface S42 is a plane.Second lens 32 are a concave-convex lens.The concrete numerical value such as the following table of each element are listed:

The surface sequence number	Radius-of-curvature (mm) (Radius of Curvature)	Distance/thickness (mm) (Distance/Thickness)	Refractive index (Nd)	Abbe number (Vd)
					S0		∞
S12	-6.0	1.05	1.5136	57.4
					S22	2.04	1.80
S32	9.184	2.843	1.5136	57.4
					S42	∞	-3.0	1.5136	57.4
S52	2.216	-1.5
					S62	∞	-0.206
S72	5.204	-0.7	1.536	57.4
					S82	1.732	-2.12
S92	∞	-0.8	1.51633	64.1
					S102	∞

Illustrate: in last table,, therefore negative spacing is arranged because of rotated 90 degree in the reflecting surface S42 place of prism 22 coordinate system.

Among the numerical value embodiment two, first lens 12, prism 22 and second lens 32 are aspheric mirror, satisfy following aspheric surface formula:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="ch"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">ch</figure-callout>}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{<figure-callout\; id="4"\; label="Ah"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">Ah</figure-callout>}}^4+{\mathrm{<figure-callout\; id="6"\; label="Bh"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">Bh</figure-callout>}}^6+{\mathrm{Ch}}^8+{\mathrm{Dh}}^{10}$

Wherein, z be along optical axis direction highly for the position of h with the surface vertices shift value apart from optical axis for referencial use, k is the tapering constant, c represents the inverse of radius-of-curvature, and h represents the eyeglass height, and A, B, C, D are asphericity coefficient, A represents the quadravalence asphericity coefficient, B represents six rank asphericity coefficients, and C represents eight rank asphericity coefficients, and D represents ten rank asphericity coefficients.

Particularly, two surperficial S12, the S22 of first lens 12, the plane of incidence S32 and the exit facet S52 of prism 22, and two surperficial S72, the S82 of second lens 32 be aspheric surface, its aspheric correlation values is listed in the table below successively:

The correlated performance index such as the following table of the minisize image acquisition lens of implementing according to numerical value embodiment two:

Whole effective focal length (f)	1.33mm
		Field of View(F.O.V)	132degree
Total Length of Lens System	14.0mm
		F-number	2.89
|f1/f|	2.14
		f2/f	3.17
f3/f	3.56

As seen from the above table, the focal length ratio that is limited to (3) by relational expression (1) | f1/f| is 2.14, and f2/f is 3.17, and f3/f is 3.56, all is positioned at desired bound scope.

Fig. 8 to Figure 11 has shown longitudinal spherical aberration, the curvature of field, distortion and the lateral chromatic aberration curve map of the camera lens of numerical value embodiment two of the present invention respectively, shows that the camera lens of numerical value embodiment two of the present invention has preferable optical appearance.

Numerical value embodiment three

As shown in figure 12, the embodiment three of minisize image acquisition lens of the present invention comprises free curved surface prism 23, an aperture diaphragm 53 of negative dioptric first lens 13, a positive diopter, second lens 33, a glass plate 63 and an imaging surface 43 of a positive diopter.First lens 13 are a biconcave lens.The plane of incidence S33 and the exit facet S53 of free curved surface prism 23 are convex surface, and reflecting surface S43 is a plane.Second lens 33 are a concave-convex lens.The concrete numerical value such as the following table of each element are listed:

The surface sequence number	Radius-of-curvature (mm) (Radius of Curvature)	Distance/thickness (mm) (Distance/Thickness)	Refractive index (Nd)	Abbe number (Vd)
					S0		∞
S13	-4.40	1.1	1.5136	57.4
					S23	1.90	1.70
S33	3.714	2.463	1.5136	57.4
					S43	∞	-2.643	1.5136	57.4
S53	2.698	-1.448
					S63	∞	-0.1
S73	-1.244	-0.7	1.536	57.4
					S83	-2.508	-1.289
S93	∞	-0.8	1.51633	64.1
					S103	∞

Illustrate: in last table,, therefore negative spacing is arranged because of rotated 90 degree in the reflecting surface S43 place of prism 23 coordinate system.

Among the numerical value embodiment three, first lens 13, prism 23 and second lens 33 are aspheric mirror, satisfy following aspheric surface formula:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="ch"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">ch</figure-callout>}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{<figure-callout\; id="4"\; label="Ah"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">Ah</figure-callout>}}^4+{\mathrm{<figure-callout\; id="6"\; label="Bh"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">Bh</figure-callout>}}^6{+\mathrm{Ch}}^8+{\mathrm{Dh}}^{10}$

Wherein, z be along optical axis direction highly for the position of h with the surface vertices shift value apart from optical axis for referencial use, k is the tapering constant, c represents the inverse of radius-of-curvature, and h represents the eyeglass height, and A, B, C, D are asphericity coefficient, A represents the quadravalence asphericity coefficient, B represents six rank asphericity coefficients, and C represents eight rank asphericity coefficients, and D represents ten rank asphericity coefficients.

Particularly, two surperficial S13, the S23 of first lens 13, the plane of incidence S33 and the exit facet S53 of prism 23, and two surperficial S73, the S83 of second lens 33 be aspheric surface, its aspheric correlation values is listed in the table below successively:

The correlated performance index such as the following table of the minisize image acquisition lens of implementing according to numerical value embodiment three:

Whole effective focal length (f)	1.3mm
		Field of View(F.O.V)	120degree
Total Length of Lens System	12.06mm
		F-number	2.83
|f1/f|	1.88
		f2/f	3.16
f3/f	3.12

As seen from the above table, the focal length ratio that is limited to (3) by relational expression (1) | f1/f| is 1.88, and f2/f is 3.16, and f3/f is 3.12, all is positioned at desired bound scope.

Figure 13 to Figure 16 has shown longitudinal spherical aberration, the curvature of field, distortion and the lateral chromatic aberration curve map of the camera lens of numerical value embodiment three of the present invention respectively, shows that the camera lens of numerical value embodiment three of the present invention has preferable optical appearance.

Numerical value embodiment four

As shown in figure 17, the embodiment four of minisize image acquisition lens of the present invention comprises free curved surface prism 24, an aperture diaphragm 54 of negative dioptric first lens 14, a positive diopter, second lens 34, a glass plate 64 and an imaging surface 44 of a positive diopter.First lens 14 are a biconcave lens.The plane of incidence S34 and the exit facet S54 of free curved surface prism 24 are convex surface, and reflecting surface S44 is a curved surface (convex surface).Second lens 34 are a biconvex lens.The concrete numerical value such as the following table of each element are listed:

The surface sequence number	Radius-of-curvature (mm) (Radius of Curvature)	Distance/thickness (mm) (Distance/Thickness)	Refractive index (Nd)	Abbe number (Vd)
					S0		∞
S14	-3.832	1.1	1.5136	57.4
					S24	1.90	1.70
S34	3.884	2.531	1.5136	57.4
					S44	-1434.006	-2.531	1.5136	57.4
S54	2.794	-1.5
					S64	∞	-0.1
S74	-2.403	-0.7	1.51633	64.1
					S84	12.981	-1.684
S94	∞	-0.8	1.51633	64.1
					S104	∞

Illustrate: in last table,, therefore negative spacing is arranged because of rotated 90 degree in the reflecting surface S44 place of prism 24 coordinate system.

Among the numerical value embodiment four, first lens 14 and prism 24 are aspheric mirror, satisfy following aspheric surface formula:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="ch"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">ch</figure-callout>}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{<figure-callout\; id="4"\; label="Ah"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">Ah</figure-callout>}}^4+{\mathrm{<figure-callout\; id="6"\; label="Bh"\; filenames="A20061006365300231.png"\; state="\{\{state\}\}">Bh</figure-callout>}}^6+{\mathrm{Ch}}^8{+\mathrm{Dh}}^{10}$

Wherein, z be along optical axis direction highly for the position of h with the surface vertices shift value apart from optical axis for referencial use, k is the tapering constant, c represents the inverse of radius-of-curvature, and h represents the eyeglass height, and A, B, C, D are asphericity coefficient, A represents the quadravalence asphericity coefficient, B represents six rank asphericity coefficients, and C represents eight rank asphericity coefficients, and D represents ten rank asphericity coefficients.

Particularly, two surperficial S14, the S24 of first lens 14, and the plane of incidence S34 of prism 24 and exit facet S54 be aspheric surface, its aspheric correlation values is listed in down in regular turn

Table:

The correlated performance index such as the following table of the minisize image acquisition lens of implementing according to numerical value embodiment four:

Whole effective focal length (f)	1.3mm
		Field of View(F.O.V)	120degree
Total Length of Lens System	12.64m
		F-number	2.82
|f1/f|	1.7
		f2/f	3.2
f3/f	3.07

As seen from the above table, the focal length ratio that is limited to (3) by relational expression (1) | f1/f| is 1.7, and f2/f is 3.2, and f3/f is 3.07, all is positioned at desired bound scope.

Figure 18 to Figure 21 has shown longitudinal spherical aberration, the curvature of field, distortion and the lateral chromatic aberration curve map of the camera lens of numerical value embodiment four of the present invention respectively, shows that the camera lens of numerical value embodiment four of the present invention has preferable optical appearance.

Compared with prior art, minisize image acquisition lens of the present invention only is comprised of two lens and a prism, has that framework is succinct, easy to assembly, the visual angle is large, volume is little, lightweight advantage; By a free curved surface prism, optical axis can be folded to 90 degree, make light path produce turnover, thereby shorten front and back length and the reduced volume of camera lens, rectifiable various aberrations obtain good solution picture simultaneously; Adopt the glass lens of ejection formation and add aspheric surface, to replace traditional glass lens, can significantly reduce cost, and be easy to aberration correction, shorten the optics overall length of camera lens and improve yield.

It should be noted that, the present invention is a kind of minisize image acquisition lens of wide-angle, the visual angle can reach more than 120 degree, therefore be suitable as very much on-vehicle lens, surveillance or network video camera lens, certainly, optical system of the present invention also be operable in less than on the visual angles of 120 degree as general wide-angle sampling image lens. Optical system overall length of the present invention only has about 7.5mm, more is conducive to be installed on automobile, burglary-resisting system or the computer perimeter systems, even on the mobile phone. Utilize framework of the present invention not only can shorten overall length, save cost, reduce the generation of tolerance, and still can obtain better optical quality.

Claims (14)

1. minisize image acquisition lens, it is characterized in that: this minisize image acquisition lens comprises the free curved surface prism of negative dioptric first lens, a positive diopter from the object side to the image side successively, and second lens of a positive diopter, wherein this free curved surface prism comprises a plane of incidence, a reflecting surface and an exit facet, and these first lens are arranged at a side of the plane of incidence and the side that this second lens are arranged at exit facet.

2. minisize image acquisition lens as claimed in claim 1 is characterized in that this minisize image acquisition lens has entire system effective focal length f, and wherein the effective focal length of these first lens is f1, both satisfy 1.3＜| f1/f|＜2.3.

3. minisize image acquisition lens as claimed in claim 2, the effective focal length that it is characterized in that this prism is f2, satisfies 2.5＜f2/f＜5.0.

4. minisize image acquisition lens as claimed in claim 3, the effective focal length that it is characterized in that these second lens is f3, satisfies 2.5＜f3/f＜4.0.

5. minisize image acquisition lens as claimed in claim 1 is characterized in that further being provided with an aperture diaphragm between this prism and this second lens.

6. minisize image acquisition lens as claimed in claim 1 is characterized in that further being provided with a glass plate between these second lens and the picture side.

7. minisize image acquisition lens as claimed in claim 1 is characterized in that these first lens have at least one side to be aspheric surface.

8. minisize image acquisition lens as claimed in claim 7 is characterized in that this prism is equivalent to the attached asphericity coefficient that gives on a right-angle prism face.

9. minisize image acquisition lens as claimed in claim 8 is characterized in that the relative inclined light shaft setting of reflecting surface of this prism, and the plane of incidence of this prism is provided with towards object space, and the exit facet of this prism is provided with towards picture side.

10. minisize image acquisition lens as claimed in claim 9 is characterized in that the plane of incidence of this prism and exit facet are aspheric surface.

11. minisize image acquisition lens as claimed in claim 10 it is characterized in that the plane of incidence of this prism, exit facet are convex surface, and reflecting surface is a plane or a convex surface.

12. minisize image acquisition lens as claimed in claim 10 is characterized in that these second lens are a non-spherical lens.

13. minisize image acquisition lens as claimed in claim 1 is characterized in that these first lens, prism and second lens make by plastics.

14. minisize image acquisition lens as claimed in claim 1 is characterized in that these first lens and this prism are made of plastics, second lens are made by glass.

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