Detailed Description
In order to make the objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. Several embodiments of the invention are presented in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Like reference numerals refer to like elements throughout the specification.
The present invention provides an optical lens, sequentially including, from an object side to an image plane along an optical axis: the lens comprises a first lens, a second lens, a diaphragm, a third lens, a fourth lens, a fifth lens, a sixth lens and an optical filter.
The first lens has negative focal power, the object side surface of the first lens is a concave surface at a paraxial region, and the image side surface of the first lens is a concave surface;
the second lens has positive focal power, the object side surface of the second lens is convex at a paraxial region, and the image side surface of the second lens is concave;
the third lens has positive focal power, and both the object side surface and the image side surface of the third lens are convex surfaces;
the fourth lens has positive focal power, and both the object side surface and the image side surface of the fourth lens are convex surfaces;
the fifth lens has negative focal power, the object-side surface of the fifth lens is concave, and the image-side surface of the fifth lens is convex at a paraxial region;
the sixth lens element has a positive optical power, an object-side surface of the sixth lens element being convex and having at least one inflection point at a paraxial region, and an image-side surface of the sixth lens element being concave and having at least one inflection point at a paraxial region.
In some embodiments, the optical lens satisfies the following conditional expression:
-20< (R1/f)×tan(HFOV) < -5;(1)
where f denotes a focal length of the optical lens, HFOV denotes a maximum half field angle of the optical lens, and R1 denotes a radius of curvature of an object side surface of the first lens. When the condition formula (1) is satisfied, the super-large wide angle and the smaller effective focal length of the lens can be realized, the optical total length can be favorably shortened, the smaller optical distortion is realized, and the distortion correction difficulty of the optical lens can be favorably reduced.
In some embodiments, the optical lens may further satisfy the following conditional expression:
-0.1mm<(SAG1×R1)/DM1<0.4mm;(2)
where SAG1 represents the saggital height of the object-side surface of the first lens at the effective aperture, R1 represents the radius of curvature of the object-side surface of the first lens, and DM1 represents the effective aperture of the object-side surface of the first lens. The lens meets the conditional expression (2), light rays with a large visual angle can enter the lens, the protruding degree and the caliber of the center of the object side face of the first lens can be effectively controlled while the large visual angle is met, and therefore the miniaturization and the ultra-wide angle balance of the lens are better achieved.
In some embodiments, the optical lens may further satisfy the following conditional expression:
-1.5<f1/f<-0.7;(3)
-7<R1/R2<-4;(4)
where f denotes a focal length of the optical lens, f1 denotes a focal length of the first lens, R1 denotes a radius of curvature of an object-side surface of the first lens, and R2 denotes a radius of curvature of an image-side surface of the first lens. Satisfying conditional expressions (3) and (4), the surface type and the focal length of the first lens can be reasonably controlled, and the molding difficulty of the first lens can be reduced, thereby reducing the processing sensitivity and improving the yield.
In some embodiments, the optical lens may further satisfy the following conditional expression:
1.2mm< CT1+CT2<1.4mm;(5)
0.13< CT2/TTL<0.18;(6)
wherein CT1 denotes a center thickness of the first lens, CT2 denotes a center thickness of the second lens, and TTL denotes an optical total length of the optical lens. The central thicknesses of the first lens and the second lens can be reasonably controlled by satisfying the conditional expressions (5) and (6), so that the sensitivity of the optical lens is favorably reduced, the production yield is improved, the structure of the optical lens is compact, and the miniaturization of the optical lens is realized.
In some embodiments, the optical lens may further satisfy the following conditional expression:
1.5<R3/R2<6.5;(7)
where R2 denotes a radius of curvature of the image-side surface of the first lens, and R3 denotes a radius of curvature of the object-side surface of the second lens. The curvature radius of the object side surface of the second lens and the curvature radius of the image side surface of the first lens can be reasonably controlled to slow down the turning trend of light rays, and the aberration of the optical lens is favorably corrected.
In some embodiments, the optical lens may further satisfy the following conditional expression:
6<(f2+f3)/f<10;(8)
0<R4/R5<6;(9)
where f2 denotes a focal length of the second lens, f3 denotes a focal length of the third lens, f denotes a focal length of the optical lens, R4 denotes a radius of curvature of an image-side surface of the second lens, and R5 denotes a radius of curvature of an object-side surface of the third lens. The surface shapes of the second lens and the third lens can be reasonably controlled by satisfying the conditional expressions (8) and (9), so that the light has a smaller angle when entering the second lens and the third lens, and the optical distortion of the optical lens can be corrected.
In some embodiments, the optical lens may further satisfy the following conditional expression:
0.5<f3/f4<1;(10)
where f3 denotes a focal length of the third lens, and f4 denotes a focal length of the fourth lens. The optical lens meets the conditional expression (10), the focal lengths of the third lens and the fourth lens can be reasonably matched, the high-order aberration of the optical lens is favorably corrected, and the resolution quality is improved.
In some embodiments, the optical lens may further satisfy the following conditional expression:
-0.06<SAG10.1/DM10<0;(11)
wherein SAG10.1 represents the rise of the image-side surface of the fifth lens at the retroflection point, and DM10 represents the effective aperture of the image-side surface of the fifth lens. And the position of an inflection point on the image side surface of the fifth lens can be reasonably controlled by satisfying the conditional expression (11), so that the distortion of an off-axis field of view can be corrected, and the imaging quality of the optical lens is improved.
In some embodiments, the optical lens may further satisfy the following conditional expression:
1.8<CT6/CT1<2.5;(12)
0.11<CT6/TTL<0.2;(13)
wherein CT1 denotes a center thickness of the first lens, CT6 denotes a center thickness of the sixth lens, and TTL denotes an optical total length of the optical lens. When the conditional expressions (12) and (13) are met, the central thicknesses of the first lens and the sixth lens can be reasonably matched, the sensitivities of the first lens and the sixth lens are reduced, and the improvement of the resolution quality of the optical lens is facilitated.
In some embodiments, the optical lens satisfies the following conditional expression:
3.0<TTL/f<4.0;(14)
FOV>140°;(15)
wherein, TTL represents the optical total length of the optical lens, f represents the focal length of the optical lens, and FOV represents the maximum field angle of the optical lens. Satisfying the above conditional expressions (14) and (15), the lens can have a smaller overall length and focal length, and can better realize the balance between a small volume and a wide viewing angle of the lens.
In some embodiments, the optical lens may further satisfy the following conditional expression:
1<f6/f<30;(16)
1.1<CT6/ET6<1.5;(17)
where f6 denotes a focal length of the sixth lens, f denotes a focal length of the optical lens, CT6 denotes a center thickness of the sixth lens, and ET6 denotes a thickness of the sixth lens at an effective aperture. The surface type of the sixth lens element can be reasonably controlled by satisfying the conditional expressions (16) and (17), so that the refraction degree of light rays can be favorably reduced, and the relative illumination of the lens is improved.
In some embodiments, the optical lens may further satisfy the following conditional expression:
2< CT23/CT34<8;(18)
where CT23 denotes a distance between the second lens and the third lens on the optical axis, and CT34 denotes a distance between the third lens and the fourth lens on the optical axis. Satisfy conditional expression (18), can rationally control the air interval between second lens to the fourth lens, effectively adjust the distribution of light, reduce optical lens's sensitivity, can also make the structure of camera lens compacter simultaneously.
In one embodiment, the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element may all be aspheric lens elements, or may be a combination of spherical and non-curved lens elements; optionally, the lenses are aspheric lenses, so that the number of lenses can be effectively reduced, aberration can be corrected, and better optical performance can be provided.
The invention is further illustrated below in the following examples. In various embodiments, the thickness, the curvature radius, and the material selection of each lens in the optical lens are different, and the specific differences can be referred to in the parameter tables of the various embodiments. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the innovative points of the present invention should be construed as being equivalent substitutions and shall be included within the scope of the present invention.
In each embodiment of the present invention, when the lenses in the optical lens are aspherical lenses, each aspherical surface type satisfies the following equation:
wherein z is the distance rise from the aspheric surface vertex when the aspheric surface is at the position of height h along the optical axis direction, c is the paraxial curvature of the surface, k is conic coefficient, A2iIs the aspheric surface type coefficient of 2i order.
First embodiment
Referring to fig. 1, a schematic structural diagram of an optical lens 100 according to a first embodiment of the present invention is shown, where the optical lens 100 sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, a stop ST, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a filter G1.
The first lens element L1 has negative power, the object-side surface S1 of the first lens element is concave at the paraxial region and convex at a distance from the optical axis, and the image-side surface S2 of the first lens element is concave;
the second lens L2 has positive optical power, the object-side surface S3 of the second lens is convex at the paraxial region, and the image-side surface S4 of the second lens is concave;
the third lens L3 has positive optical power, and both the object-side surface S5 and the image-side surface S6 of the third lens are convex;
the fourth lens L4 has positive power, and both the fourth object-side surface S7 and the fourth image-side surface S8 are convex;
the fifth lens element L5 has a negative power, the object-side surface S9 of the fifth lens element is concave, the image-side surface S10 of the fifth lens element is convex at paraxial region, and the vertical distance between the point of inflection on the image-side surface S10 of the fifth lens element and the optical axis is 0.513 mm, and the sagittal height is-0.024 mm.
The sixth lens element L6 has positive optical power, an object-side surface S11 of the sixth lens element is convex at the paraxial region and has at least one inflection point, and an image-side surface S12 of the sixth lens element is concave at the paraxial region and has at least one inflection point.
In order to correct the aberration of the system better, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are all plastic aspheric lenses.
Specifically, the first embodiment of the present invention provides an optical lens 100 in which the relevant parameters of each lens are shown in table 1.
TABLE 1
The surface shape coefficients of the aspherical surfaces of the optical lens 100 in the present embodiment are shown in table 2.
TABLE 2
Referring to fig. 2, fig. 3 and fig. 4, a distortion curve, a vertical axis chromatic aberration curve and an axial chromatic aberration curve of the optical lens 100 are respectively shown.
The distortion curve of fig. 2 represents the distortion at different image heights on the imaging plane. In fig. 2, the horizontal axis represents the distortion percentage, and the vertical axis represents the angle of view (unit: degree). As can be seen from fig. 2, the f- θ distortion at different image heights on the image plane is controlled to be within 10%, which indicates that the distortion of the optical lens 100 is well corrected.
The vertical axis chromatic aberration curve of fig. 3 shows chromatic aberration at different image heights on the image forming surface for the longest wavelength and the shortest wavelength. In fig. 3, the horizontal axis represents the homeotropic color difference (unit: μm) of each wavelength with respect to the center wavelength, and the vertical axis represents the normalized angle of view. As can be seen from fig. 3, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 2.3 microns, which indicates that the optical lens 100 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.
The axial chromatic aberration curve of fig. 4 represents the aberration on the optical axis at the imaging plane. In fig. 4, the horizontal axis represents a spherical value (unit: μm), and the vertical axis represents a normalized pupil radius. As can be seen from fig. 4, the offset of the axial chromatic aberration is controlled within ± 0.02 mm, which indicates that the axial chromatic aberration of the optical lens 100 is well corrected.
Second embodiment
Referring to fig. 5, a schematic structural diagram of an optical lens 200 according to a second embodiment of the present invention is shown, where the optical lens 200 according to the second embodiment of the present invention has substantially the same structure as the optical lens 100 according to the first embodiment, and mainly differs in the radius of curvature and material selection of each lens.
In the optical lens 200 of the present invention, the vertical distance between the inflection point of the image-side surface S10 of the fifth lens and the optical axis is 0.573 mm, and the sagittal height is-0.036 mm.
Specifically, the second embodiment of the present invention provides an optical lens 200, in which the relevant parameters of each lens are shown in table 3.
TABLE 3
The surface shape coefficients of the aspherical surfaces of the optical lens 200 in the present embodiment are shown in table 4.
TABLE 4
Referring to fig. 6, 7 and 8, a distortion curve, a vertical axis chromatic aberration curve and an axial chromatic aberration curve of the optical lens 200 are shown, respectively.
Fig. 6 shows the distortion at different image heights on the imaging plane. As can be seen from fig. 6, the f- θ distortion at different image heights on the image plane is controlled within 10.5%, which indicates that the distortion of the optical lens 200 is well corrected.
Fig. 7 shows chromatic aberration at different image heights on the image forming surface for the longest wavelength and the shortest wavelength. As can be seen from fig. 7, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 2.5 microns, which indicates that the optical lens 200 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.
Fig. 8 shows aberrations on the optical axis at the imaging plane. As can be seen from fig. 8, the offset of the axial chromatic aberration is controlled within ± 0.02 mm, which indicates that the axial chromatic aberration of the optical lens 200 is well corrected.
Third embodiment
Referring to fig. 9, a schematic structural diagram of an optical lens 300 according to a third embodiment of the present invention is shown, where the optical lens 300 according to the third embodiment of the present invention has substantially the same structure as the optical lens 100 according to the first embodiment, and mainly differs in the radius of curvature and material selection of each lens.
In the optical lens 300 of the present invention, the vertical distance between the inflection point of the image-side surface S10 of the fifth lens element and the optical axis is 0.509 mm, and the sagittal height is-0.014 mm.
Specifically, the third embodiment of the present invention provides an optical lens 300, in which the relevant parameters of each lens are shown in table 5.
TABLE 5
The surface shape coefficients of the aspherical surfaces of the optical lens 300 in the present embodiment are shown in table 6.
TABLE 6
Referring to fig. 10, 11 and 12, a distortion curve, a vertical axis chromatic aberration curve and an axial chromatic aberration curve of the optical lens 300 are shown, respectively.
Fig. 10 shows distortion at different image heights on the imaging plane. As can be seen from fig. 10, the f- θ distortion at different image heights on the image plane is controlled to be within 10%, which indicates that the distortion of the optical lens 300 is well corrected.
Fig. 11 shows chromatic aberration at different image heights on the image forming surface for the longest wavelength and the shortest wavelength. As can be seen from fig. 11, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ± 3.0 microns, which indicates that the optical lens 300 can effectively correct the aberration of the fringe field and the secondary spectrum of the entire image plane.
Fig. 12 shows aberrations on the optical axis at the imaging plane. As can be seen from fig. 12, the shift amount of the axial chromatic aberration at the image plane is controlled within ± 0.015 mm, which indicates that the axial chromatic aberration of the optical lens 300 is well corrected.
Referring to table 7, optical characteristics corresponding to the optical lenses provided in the three embodiments are shown. The optical characteristics mainly include a focal length F, an F # of the optical lens, an entrance pupil diameter EPD, a total optical length TTL, and a field angle FOV of the optical lens, and a correlation value corresponding to each of the aforementioned conditional expressions.
TABLE 7
In summary, the optical lens provided by the invention has at least the following advantages:
(1) because the shapes of the diaphragm and each lens are reasonably arranged, on one hand, the optical lens has a smaller entrance pupil diameter, so that the outer diameter of the head part of the lens can be smaller, and the requirement of high screen ratio is met; on the other hand, the total length of the optical lens is shorter (TTL <5.8 mm), the volume is reduced, and the development trend of light and thin portable intelligent electronic products such as mobile phones can be better met.
(2) Six plastic aspheric lenses with specific focal power are adopted, and the lenses are matched through specific surface shapes, so that the optical lens has ultrahigh pixel imaging quality, can be matched with a CMOS chip with 800 ten thousand pixels, and is favorable for clear imaging.
(3) The surface type of the first lens is reasonable, so that the field angle of the optical lens can reach more than 150 degrees; meanwhile, the focal power and the surface type of each lens are reasonably arranged, the optical distortion can be effectively corrected, the f-theta distortion is controlled within 11 percent, and the use requirements of large field angle and high-definition imaging can be met.
According to the optical lens provided by the invention, through reasonable collocation of six lenses with specific focal power and lens shapes, the structure is more compact while high pixel is met, so that the miniaturization and high pixel balance of the wide-angle lens are better realized, the wide-angle lens has a large field angle, and the shooting experience of a user can be effectively improved.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.