CN110908085B

CN110908085B - Image pickup optical lens

Info

Publication number: CN110908085B
Application number: CN201911344461.XA
Authority: CN
Inventors: 李晚侠
Original assignee: Chengrui Optics Changzhou Co Ltd
Current assignee: Chengrui Optics Changzhou Co Ltd
Priority date: 2019-12-23
Filing date: 2019-12-23
Publication date: 2021-12-14
Anticipated expiration: 2039-12-23
Also published as: CN110908085A

Abstract

The invention relates to the field of optical lenses, and discloses an image pickup optical lens, which sequentially comprises from an object side to an image side: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens; and satisfies the following relationships: f1/f is more than or equal to 0.78 and less than or equal to 1.35; f2 is less than or equal to 0 mm; (R7+ R8)/(R7-R8) is not more than 0.20 and not more than 0.90; d5/d6 is more than or equal to 3.80 and less than or equal to 15.00. The camera optical lens has good optical performance such as large aperture, large wide angle, ultrathin property and the like.

Description

Image pickup optical lens

Technical Field

The present invention relates to the field of optical lenses, and more particularly, to an imaging optical lens suitable for portable terminal devices such as smart phones and digital cameras, and imaging apparatuses such as monitors and PC lenses.

Background

In recent years, with the rise of smart phones, the demand of miniaturized camera lenses is increasing, and the photosensitive devices of general camera lenses are not limited to two types, namely, a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) Device, and due to the refinement of Semiconductor manufacturing technology, the pixel size of the photosensitive devices is reduced, and in addition, the current electronic products are developed in a form of being excellent in function, light, thin, short and small, so that the miniaturized camera lenses with good imaging quality are the mainstream in the current market.

In order to obtain better imaging quality, the lens mounted on the mobile phone camera conventionally adopts a three-piece or four-piece lens structure. Moreover, with the development of technology and the increase of diversified demands of users, under the condition that the pixel area of the photosensitive device is continuously reduced and the requirement of the system on the imaging quality is continuously improved, five-piece, six-piece, seven-piece and eight-piece lens structures gradually appear in the design of the lens. An ultra-thin wide-angle imaging optical lens having excellent optical characteristics is urgently required.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an imaging optical lens that can satisfy the requirements of a large aperture, an ultra-thin thickness, and a wide angle while achieving high imaging performance.

To solve the above-mentioned problems, an embodiment of the present invention provides an imaging optical lens, in order from an object side to an image side, comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens;

the focal length of the imaging optical lens is f, the focal length of the first lens is f1, the focal length of the second lens is f2, the curvature radius of the object side surface of the fourth lens is R7, the curvature radius of the image side surface of the fourth lens is R8, the on-axis thickness of the third lens is d5, and the on-axis distance from the image side surface of the third lens to the object side surface of the fourth lens is d6, so that the following relational expression is satisfied:

0.78≤f1/f≤1.35；

f2≤0mm；

0.20≤(R7+R8)/(R7-R8)≤0.90；

3.80≤d5/d6≤15.00。

preferably, the focal length of the seventh lens is f7, and the following relation is satisfied:

1.05≤f7/f≤3.00。

preferably, the curvature radius of the object-side surface of the first lens element is R1, the curvature radius of the image-side surface of the first lens element is R2, the on-axis thickness of the first lens element is d1, and the total optical length of the imaging optical lens system is TTL and satisfies the following relationship:

-5.03≤(R1+R2)/(R1-R2)≤-0.71；

0.04≤d1/TTL≤0.15。

preferably, the curvature radius of the object-side surface of the second lens element is R3, the curvature radius of the image-side surface of the second lens element is R4, the on-axis thickness of the second lens element is d3, and the total optical length of the imaging optical lens system is TTL and satisfies the following relationship:

-3.17≤f2/f≤-1.01；

1.25≤(R3+R4)/(R3-R4)≤6.49；

0.01≤d3/TTL≤0.04。

preferably, the focal length of the third lens element is f3, the radius of curvature of the object-side surface of the third lens element is R5, the radius of curvature of the image-side surface of the third lens element is R6, and the total optical length of the imaging optical lens system is TTL and satisfies the following relationship:

0.58≤f3/f≤529.61；

-2.15≤(R5+R6)/(R5-R6)≤432.12；

0.04≤d5/TTL≤0.19。

preferably, the focal length of the fourth lens element is f4, the on-axis thickness of the fourth lens element is d7, the total optical length of the imaging optical lens is TTL, and the following relationship is satisfied:

1.56≤f4/f≤6.31；

0.02≤d7/TTL≤0.08。

preferably, the focal length of the fifth lens element is f5, the curvature radius of the object-side surface of the fifth lens element is R9, the curvature radius of the image-side surface of the fifth lens element is R10, the on-axis thickness of the fifth lens element is d9, the total optical length of the imaging optical lens assembly is TTL, and the following relationships are satisfied:

1.62≤f5/f≤6.23；

0.99≤(R9+R10)/(R9-R10)≤3.32；

0.04≤d9/TTL≤0.18。

preferably, the focal length of the sixth lens element is f6, the curvature radius of the object-side surface of the sixth lens element is R11, the curvature radius of the image-side surface of the sixth lens element is R12, the on-axis thickness of the sixth lens element is d11, the total optical length of the imaging optical lens assembly is TTL, and the following relationships are satisfied:

-7.70≤f6/f≤-2.31；

-14.42≤(R11+R12)/(R11-R12)≤-1.81；

0.01≤d11/TTL≤0.10。

preferably, a curvature radius of an object-side surface of the seventh lens element is R13, a curvature radius of an image-side surface of the seventh lens element is R14, an on-axis thickness of the seventh lens element is d13, and an optical total length of the imaging optical lens system is TTL and satisfies the following relational expression:

0.09≤(R13+R14)/(R13-R14)≤0.48；

0.05≤d13/TTL≤0.25。

preferably, the focal length of the eighth lens element is f8, the curvature radius of the object-side surface of the eighth lens element is R15, the curvature radius of the image-side surface of the eighth lens element is R16, the on-axis thickness of the eighth lens element is d15, the total optical length of the imaging optical lens system is TTL, and the following relationships are satisfied:

-1.37≤f8/f≤-0.35；

0.06≤(R15+R16)/(R15-R16)≤1.03；

0.02≤d15/TTL≤0.11。

the invention has the beneficial effects that: the pick-up optical lens according to the present invention has excellent optical characteristics, satisfies the requirements of large aperture, ultra-thinning and wide angle of view, and is particularly suitable for a mobile phone pick-up lens assembly and a WEB pick-up lens which are composed of pick-up elements such as high-pixel CCDs and CMOSs.

Drawings

Fig. 1 is a schematic configuration diagram of an imaging optical lens according to a first embodiment of the present invention;

FIG. 2 is a schematic axial aberration diagram of the imaging optical lens of FIG. 1;

fig. 3 is a schematic diagram of chromatic aberration of magnification of the imaging optical lens shown in fig. 1;

FIG. 4 is a schematic view of curvature of field and distortion of the imaging optical lens of FIG. 1;

fig. 5 is a schematic configuration diagram of an imaging optical lens according to a second embodiment of the present invention;

FIG. 6 is a schematic axial aberration diagram of the imaging optical lens of FIG. 5;

fig. 7 is a schematic diagram of chromatic aberration of magnification of the imaging optical lens shown in fig. 5;

FIG. 8 is a schematic view of curvature of field and distortion of the imaging optical lens of FIG. 5;

fig. 9 is a schematic configuration diagram of an imaging optical lens according to a third embodiment of the present invention;

fig. 10 is a schematic view of axial aberrations of the image pickup optical lens shown in fig. 9;

fig. 11 is a schematic diagram of chromatic aberration of magnification of the imaging optical lens shown in fig. 9;

fig. 12 is a schematic view of curvature of field and distortion of the imaging optical lens shown in fig. 9.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that numerous technical details are set forth in order to provide a better understanding of the present invention in its various embodiments. However, the technical solution claimed in the present invention can be implemented without these technical details and various changes and modifications based on the following embodiments.

(first embodiment)

Referring to the drawings, the present invention provides an image pickup optical lens 10. Fig. 1 shows an imaging optical lens 10 according to a first embodiment of the present invention, and the imaging optical lens 10 includes eight lenses. Specifically, the imaging optical lens 10, in order from an object side to an image side, includes: the stop S1, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8. An optical element such as an optical filter (filter) GF may be disposed between the eighth lens L8 and the image plane Si.

Defining the focal length of the entire image pickup optical lens 10 as f, and the focal length of the first lens L1 as f1, the following relations are satisfied: f1/f is more than or equal to 0.78 and less than or equal to 1.35. Thus, the ratio of the focal length of the first lens L1 to the total focal length of the system is defined, and the spherical aberration and the field curvature of the system can be effectively balanced.

Defining the focal length of the second lens L2 as f2, the relation is satisfied: f2 is less than or equal to 0 mm. Therefore, the focal length of the second lens L2 is defined to be positive or negative, and the system has better imaging quality and lower sensitivity through reasonable distribution of the focal length. Preferably, f2 is less than or equal to 6.46 mm.

The curvature radius of the object-side surface of the fourth lens L4 is defined as R7, the curvature radius of the image-side surface of the fourth lens L4 is defined as R8, and the following relation is satisfied: the ratio of (R7+ R8)/(R7-R8) is not more than 0.20 and not more than 0.90. Thus, the shape of the fourth lens L4 is defined, and the degree of deflection of the light rays passing through the lens can be reduced within the range defined by the conditional expression, thereby effectively reducing the aberration. Preferably, the following are satisfied: the ratio of (R7+ R8)/(R7-R8) is not more than 0.21 and not more than 0.89.

Defining the on-axis thickness of the third lens L3 as d5, and the on-axis distance from the image-side surface of the third lens L3 to the object-side surface of the fourth lens L4 as d6, the following relations are satisfied: d5/d6 is more than or equal to 3.80 and less than or equal to 15.00. Thus, the ratio of the on-axis thickness of the third lens L3 to the on-axis air space of the third lens L3 and the fourth lens L4 is determined, and the total length of the optical system can be reduced within the conditional expression range, thereby achieving the effect of making the optical system thinner. Preferably, the following are satisfied: d5/d6 is more than or equal to 3.80 and less than or equal to 14.72.

When the focal length of the image-capturing optical lens 10, the focal length of each lens, the on-axis distance from the image-side surface of the relevant lens to the object-side surface, and the on-axis thickness satisfy the above relationship, the image-capturing optical lens 10 can have high performance and meet the design requirement of low TTL.

Defining the focal length of the seventh lens L7 as f7 and the focal length of the entire imaging optical lens 10 as f, the following relation is satisfied: f7/f is more than or equal to 1.05 and less than or equal to 3.00. Therefore, the ratio of the focal length of the seventh lens L7 to the total focal length of the system is specified, and the system has better imaging quality and lower sensitivity through reasonable distribution of the focal length. Preferably, the following are satisfied: f7/f is more than or equal to 1.06 and less than or equal to 2.83.

The first lens element L1 has positive refractive power. The object-side surface of the first lens element L1 is convex in the paraxial region, and the image-side surface thereof is concave in the paraxial region.

The curvature radius of the object-side surface of the first lens L1 is defined as R1, the curvature radius of the image-side surface of the first lens L1 is defined as R2, and the following relations are satisfied: -5.03 (R1+ R2)/(R1-R2) is less than or equal to-0.71. Thereby, the shape of the first lens L1 is controlled appropriately, so that the first lens L1 can effectively correct the system spherical aberration. Preferably, the following are satisfied: -3.14 ≤ (R1+ R2)/(R1-R2) ≤ 0.88.

Defining the on-axis thickness of the first lens L1 as d1, the total optical length of the imaging optical lens as TTL, and satisfying the relation: d1/TTL is more than or equal to 0.04 and less than or equal to 0.15, and ultra-thinning is facilitated. Preferably, the following are satisfied: d1/TTL is more than or equal to 0.06 and less than or equal to 0.12.

The second lens element L2 has negative refractive power. The second lens element L2 has a convex object-side surface at the paraxial region and a concave image-side surface at the paraxial region.

Defining a focal length f2 of the second lens L2, wherein f is the focal length of the entire imaging optical lens 10, and the following relation is satisfied: f2/f is not less than-3.17 and not more than-1.01. By controlling the negative power of the second lens L2 within a reasonable range, it is advantageous to correct the aberration of the optical system. Preferably, the following are satisfied: f2/f is not less than-1.98 and not more than-1.26.

The curvature radius of the object-side surface of the second lens L2 is defined as R3, the curvature radius of the image-side surface of the second lens L2 is defined as R4, and the following relation is satisfied: 1.25-6.49% (R3+ R4)/(R3-R4). The shape of the second lens L2 is defined, and when the second lens L2 is within the range, the lens is made to have a very thin and wide angle, which is advantageous for correcting the problem of on-axis aberration. Preferably, the following are satisfied: 1.99-5.19 (R3+ R4)/(R3-R4).

Defining the on-axis thickness of the second lens L2 as d3, the total optical length of the imaging optical lens as TTL, and satisfying the relation: d3/TTL is more than or equal to 0.01 and less than or equal to 0.04, which is beneficial to realizing ultra-thinning. Preferably, the following are satisfied: d3/TTL is more than or equal to 0.02 and less than or equal to 0.03.

The third lens element L3 has positive refractive power. The object-side surface of the third lens element L3 is convex at the paraxial region.

Defining the focal length of the third lens L3 as f3 and the focal length of the entire imaging optical lens 10 as f, the following relation is satisfied: f3/f is more than or equal to 0.58 and less than or equal to 529.61. Through reasonable distribution of the optical power, the system has better imaging quality and lower sensitivity. Preferably, the following are satisfied: f3/f is not less than 0.93 and not more than 423.68.

The curvature radius of the object-side surface of the third lens L3 is defined as R5, the curvature radius of the image-side surface of the third lens L3 is defined as R6, and the following relation is satisfied: -2.15 ≤ (R5+ R6)/(R5-R6) ≤ 432.12. The shape of the third lens L3 is defined, and when the third lens L3 is within the range, the lens is made to have a very thin and wide angle, which is advantageous for correcting the problem of on-axis aberration. Preferably, the following are satisfied: -1.34 ≤ (R5+ R6)/(R5-R6) ≤ 345.69.

Defining the on-axis thickness of the third lens L3 as d5, the total optical length of the imaging optical lens as TTL, and satisfying the relation: d5/TTL is more than or equal to 0.04 and less than or equal to 0.19, and ultra-thinning is facilitated. Preferably, the following are satisfied: d5/TTL is more than or equal to 0.06 and less than or equal to 0.15.

The fourth lens element L4 has positive refractive power. The fourth lens element L4 has a convex object-side surface in the paraxial region and a convex image-side surface in the paraxial region.

Defining the focal length of the fourth lens L4 as f4 and the focal length of the entire imaging optical lens 10 as f, the following relation is satisfied: f4/f is more than or equal to 1.56 and less than or equal to 6.31. Through reasonable distribution of the optical power, the system has better imaging quality and lower sensitivity. Preferably, the following are satisfied: f4/f is more than or equal to 2.50 and less than or equal to 5.05.

Defining the on-axis thickness of the fourth lens L4 as d7, the total optical length of the imaging optical lens as TTL, and satisfying the relation: d7/TTL is more than or equal to 0.02 and less than or equal to 0.08, and ultra-thinning is facilitated. Preferably, the following are satisfied: d7/TTL is more than or equal to 0.04 and less than or equal to 0.06.

The fifth lens element L5 has positive refractive power. The fifth lens element L5 has a concave object-side surface at the paraxial region and a convex image-side surface at the paraxial region.

Defining the focal length of the fifth lens L5 as f5 and the focal length of the entire imaging optical lens 10 as f, the following relation is satisfied: f5/f is more than or equal to 1.62 and less than or equal to 6.23. The definition of the fifth lens L5 can effectively make the light ray angle of the camera lens smooth, and reduce tolerance sensitivity. Preferably, the following are satisfied: f5/f is more than or equal to 2.60 and less than or equal to 4.99.

The curvature radius of the object-side surface of the fifth lens L5 is defined as R9, the curvature radius of the image-side surface of the fifth lens L5 is defined as R10, and the following relation is satisfied: not less than 0.99 and not more than (R9+ R10)/(R9-R10) and not more than 3.32. When the shape of the fifth lens L5 is defined and falls within the range defined by the relational expression, it is advantageous to correct the off-axis aberration and other problems as the angle of view increases. Preferably, the following are satisfied: 1.58 is less than or equal to (R9+ R10)/(R9-R10) is less than or equal to 2.65.

Defining the on-axis thickness of the fifth lens L5 as d9, the total optical length of the imaging optical lens as TTL, and satisfying the relation: d9/TTL is more than or equal to 0.04 and less than or equal to 0.18, and ultra-thinning is facilitated. Preferably, the following are satisfied: d9/TTL is more than or equal to 0.07 and less than or equal to 0.15.

The sixth lens element L6 has negative refractive power. The object-side surface of the sixth lens element L6 is concave in the paraxial region, and the image-side surface thereof is convex in the paraxial region.

Defining the focal length of the sixth lens L6 as f6 and the focal length of the entire imaging optical lens 10 as f, the following relation is satisfied: f6/f is not less than 7.70 and not more than-2.31. Through reasonable distribution of the optical power, the system has better imaging quality and lower sensitivity. Preferably, the following are satisfied: f6/f is not less than 4.81 and not more than 2.88.

The curvature radius of the object-side surface of the sixth lens L6 is defined as R11, the curvature radius of the image-side surface of the sixth lens L6 is defined as R12, and the following relation is satisfied: -14.42 ≦ (R11+ R12)/(R11-R12) ≦ -1.81. When the shape of the sixth lens L6 is defined and falls within the range defined by the relational expression, it is advantageous to correct the off-axis aberration and other problems as the angle of view increases with the increase in the thickness and the angle of view. Preferably, the following are satisfied: the ratio of (R11+ R12)/(R11-R12) is not more than-9.01 and not more than-2.26.

Defining the on-axis thickness of the sixth lens L6 as d11, the total optical length of the imaging optical lens as TTL, and satisfying the relation: d11/TTL is more than or equal to 0.01 and less than or equal to 0.10, and ultra-thinning is facilitated. Preferably, the following are satisfied: d11/TTL is more than or equal to 0.02 and less than or equal to 0.08.

The seventh lens element L7 has positive refractive power. The object-side surface of the seventh lens element L7 is convex in the paraxial region, and the image-side surface thereof is convex in the paraxial region.

The curvature radius of the object-side surface of the seventh lens L7 is defined as R13, the curvature radius of the image-side surface of the seventh lens L7 is defined as R14, and the following relations are satisfied: the ratio of (R13+ R14)/(R13-R14) is not more than 0.09 and not more than 0.48. When the shape of the seventh lens L7 is defined and falls within the range defined by the relational expression, it is advantageous to correct the off-axis aberration and other problems as the angle of view increases. Preferably, the following are satisfied: 0.14-0.39 of (R13+ R14)/(R13-R14).

Defining the on-axis thickness of the seventh lens L7 as d13, the total optical length of the imaging optical lens as TTL, and satisfying the relation: d13/TTL is more than or equal to 0.05 and less than or equal to 0.25, and ultra-thinning is facilitated. Preferably, the following are satisfied: d13/TTL is more than or equal to 0.08 and less than or equal to 0.20.

The eighth lens element L8 has negative refractive power. The object-side surface of the eighth lens element L8 is concave in the paraxial region and the image-side surface is concave in the paraxial region.

Defining the focal length of the eighth lens L8 as f8 and the focal length of the entire imaging optical lens 10 as f, the following relation is satisfied: f8/f is more than or equal to-1.37 and less than or equal to-0.35. By controlling the negative power of the eighth lens L8 within a reasonable range, it is advantageous to correct the aberration of the optical system. Preferably, the following are satisfied: f8/f is more than or equal to-0.85 and less than or equal to-0.44.

The curvature radius of the object-side surface of the eighth lens element L8 is defined as R15, the curvature radius of the image-side surface of the eighth lens element L8 is defined as R16, and the following relations are satisfied: not less than 0.06 (R15+ R16)/(R15-R16) not more than 1.03. The shape of the eighth lens L8 is defined, and when the shape is within the range defined by the relational expression, molding of the eighth lens L8 is facilitated, and molding failure and stress generation due to an excessively large surface curvature of the eighth lens L8 are avoided. Preferably, the following are satisfied: the ratio of (R15+ R16)/(R15-R16) is not more than 0.09 and not more than 0.83.

Defining the on-axis thickness of the eighth lens L8 as d15, the total optical length of the imaging optical lens as TTL, and satisfying the relation: d15/TTL is more than or equal to 0.02 and less than or equal to 0.11, and ultra-thinning is facilitated. Preferably, the following are satisfied: d15/TTL is more than or equal to 0.04 and less than or equal to 0.08.

In the present embodiment, the combined focal length of the first lens L1 and the second lens L2 is defined as f12, and the focal length of the entire imaging optical lens 10 is defined as f, which satisfies the following relation: f12/f is more than or equal to 0.70 and less than or equal to 9.01. Within the range of the relational expression, the aberration and distortion of the image pickup optical lens 10 can be eliminated, and the back focal length of the image pickup optical lens 10 can be suppressed, thereby maintaining the miniaturization of the image lens system. Preferably, the following are satisfied: f12/f is more than or equal to 1.11 and less than or equal to 7.21.

In the present embodiment, the total optical length TTL of the imaging optical lens 10 is less than or equal to 11.73 millimeters. Preferably, the total optical length TTL is less than or equal to 11.19 millimeters.

With such a design, the total optical length TTL of the entire imaging optical lens 10 can be made as short as possible, and the characteristic of miniaturization can be maintained.

In this embodiment, the image height is IH, and IH and TTL satisfy the following relation: TTL/IH is less than or equal to 1.67, and ultra-thinning of the shooting optical lens 10 is realized.

In the present embodiment, the number of the diaphragm F of the imaging optical lens 10 is 1.91 or less, and the imaging optical lens 10 has a large diaphragm and is excellent in image forming performance.

In the present embodiment, the imaging optical lens 10 has a wide angle of view FOV not less than 72 °.

The image pickup optical lens 10 of the present invention will be explained below by way of example. The symbols described in the respective examples are as follows. The units of focal length, on-axis distance, radius of curvature, on-axis thickness, location of the inflection point, and location of the stagnation point are millimeters (mm).

TTL: the optical length (on-axis distance from the object side surface of the first lens L1 to the image forming surface) is in units of millimeters (mm).

Preferably, the object side surface and/or the image side surface of the lens may be provided with an inflection point and/or a stagnation point to meet the requirement of high-quality imaging, and specific embodiments are described below.

Tables 1 and 2 show design data of the imaging optical lens 10 according to the first embodiment of the present invention.

[ TABLE 1 ]

Wherein each symbol has the following meaning.

S1: an aperture;

r: the radius of curvature of the optical surface and the radius of curvature of the lens as the center;

r1: the radius of curvature of the object-side surface of the first lens L1;

r2: the radius of curvature of the image-side surface of the first lens L1;

r3: the radius of curvature of the object-side surface of the second lens L2;

r4: the radius of curvature of the image-side surface of the second lens L2;

r5: the radius of curvature of the object-side surface of the third lens L3;

r6: the radius of curvature of the image-side surface of the third lens L3;

r7: the radius of curvature of the object-side surface of the fourth lens L4;

r8: the radius of curvature of the image-side surface of the fourth lens L4;

r9: a radius of curvature of the object side surface of the fifth lens L5;

r10: a radius of curvature of the image-side surface of the fifth lens L5;

r11: a radius of curvature of the object side surface of the sixth lens L6;

r12: a radius of curvature of the image-side surface of the sixth lens L6;

r13: a radius of curvature of the object side surface of the seventh lens L7;

r14: a radius of curvature of the image-side surface of the seventh lens L7;

r15: a radius of curvature of the object side surface of the eighth lens L8;

r16: a radius of curvature of the image-side surface of the eighth lens L8;

r17: radius of curvature of the object side of the optical filter GF;

r18: the radius of curvature of the image-side surface of the optical filter GF;

d: an on-axis thickness of the lenses and an on-axis distance between the lenses;

d 0: the on-axis distance of the stop S1 to the object-side surface of the first lens L1;

d 1: the on-axis thickness of the first lens L1;

d 2: the on-axis distance from the image-side surface of the first lens L1 to the object-side surface of the second lens L2;

d 3: the on-axis thickness of the second lens L2;

d 4: the on-axis distance from the image-side surface of the second lens L2 to the object-side surface of the third lens L3;

d 5: the on-axis thickness of the third lens L3;

d 6: the on-axis distance from the image-side surface of the third lens L3 to the object-side surface of the fourth lens L4;

d 7: the on-axis thickness of the fourth lens L4;

d 8: an on-axis distance from an image-side surface of the fourth lens L4 to an object-side surface of the fifth lens L5;

d 9: the on-axis thickness of the fifth lens L5;

d 10: an on-axis distance from an image-side surface of the fifth lens L5 to an object-side surface of the sixth lens L6; d 11: the on-axis thickness of the sixth lens L6;

d 12: an on-axis distance from the image-side surface of the sixth lens L6 to the object-side surface of the seventh lens L7;

d 13: the on-axis thickness of the seventh lens L7;

d 14: an on-axis distance from the image-side surface of the seventh lens L7 to the object-side surface of the eighth lens L8;

d 15: the on-axis thickness of the eighth lens L8;

d 16: the on-axis distance from the image-side surface of the eighth lens L8 to the object-side surface of the optical filter GF;

d 17: on-axis thickness of the optical filter GF;

d 18: the axial distance from the image side surface of the optical filter GF to the image surface Si;

nd: the refractive index of the d-line;

nd 1: the refractive index of the d-line of the first lens L1;

nd 2: the refractive index of the d-line of the second lens L2;

nd 3: the refractive index of the d-line of the third lens L3;

nd 4: the refractive index of the d-line of the fourth lens L4;

nd 5: the refractive index of the d-line of the fifth lens L5;

nd 6: the refractive index of the d-line of the sixth lens L6;

nd 7: the refractive index of the d-line of the seventh lens L7;

nd 8: the refractive index of the d-line of the eighth lens L8;

ndg: the refractive index of the d-line of the optical filter GF;

vd: an Abbe number;

v 1: abbe number of the first lens L1;

v 2: abbe number of the second lens L2;

v 3: abbe number of the third lens L3;

v 4: abbe number of the fourth lens L4;

v 5: abbe number of the fifth lens L5;

v 6: abbe number of the sixth lens L6;

v 7: abbe number of the seventh lens L7;

v 8: abbe number of the eighth lens L8;

vg: abbe number of the optical filter GF.

Table 2 shows aspherical surface data of each lens in the imaging optical lens 10 according to the first embodiment of the present invention.

[ TABLE 2 ]

Wherein k is a conic coefficient, and A4, A6, A8, A10, A12, A14, A16, A18, A20 are aspheric coefficients.

IH: image height

y＝(x²/R)/[1+{1-(k+1)(x²/R²)}1/2]+A4x⁴+A6x⁶+A8x⁸+A10x¹⁰+A12x¹²+A14x¹⁴+A16x¹⁶+A18x¹⁸+A20x²⁰。 (1)

For convenience, the aspherical surface of each lens surface uses the aspherical surface shown in the above formula (1). However, the present invention is not limited to the aspherical polynomial form expressed by this formula (1).

Tables 3 and 4 show the inflection point and stagnation point design data of each lens in the imaging optical lens 10 according to the first embodiment of the present invention. Wherein P1R1 and P1R2 represent the object-side surface and the image-side surface of the first lens L1, P2R1 and P2R2 represent the object-side surface and the image-side surface of the second lens L2, P3R1 and P3R2 represent the object-side surface and the image-side surface of the third lens L3, P4R1 and P4R2 represent the object-side surface and the image-side surface of the fourth lens L4, P5R1 and P5R2 represent the object-side surface and the image-side surface of the fifth lens L5, P6R1 and P6R2 represent the object-side surface and the image-side surface of the sixth lens L6, P7R1 and P7R2 represent the object-side surface and the image-side surface of the seventh lens L7, and P8R1 and P8R2 represent the object-side surface and the image-side surface of the eighth lens L8, respectively. The "inflection point position" field correspondence data is a vertical distance from an inflection point set on each lens surface to the optical axis of the imaging optical lens 10. The "stagnation point position" field corresponding data is the vertical distance from the stagnation point set on each lens surface to the optical axis of the imaging optical lens 10.

[ TABLE 3 ]

[ TABLE 4 ]

	Number of stagnation points	Location of stagnation 1	Location of stagnation 2
				P1R1
P1R2
				P2R1
P2R2
				P3R1	1	2.345
P3R2
				P4R1	1	0.185
P4R2
				P5R1
P5R2
				P6R1
P6R2
				P7R1	1	1.415
P7R2	2	1.115	1.975
				P8R1
P8R2	1	3.405

Fig. 2 and 3 are schematic diagrams showing axial aberrations and chromatic aberration of magnification of light having wavelengths of 656nm, 587nm, 546nm, 486nm, and 436nm passing through the imaging optical lens 10 according to the first embodiment. Fig. 4 is a schematic view showing the field curvature and distortion of light having a wavelength of 546nm after passing through the imaging optical lens 10 according to the first embodiment, where in fig. 4, the field curvature S is the field curvature in the sagittal direction, and T is the field curvature in the tangential direction.

Table 13 shown later shows values of various numerical values in examples 1, 2, and 3 corresponding to the parameters specified in the conditional expressions.

As shown in table 13, the first embodiment satisfies each conditional expression.

In the present embodiment, the imaging optical lens 10 has an entrance pupil diameter of 4.471mm, a full field height of 6.400mm, a diagonal field angle of 73.10 °, and is sufficiently corrected for on-axis and off-axis chromatic aberration and has excellent optical characteristics, because the imaging optical lens 10 has a wide angle of view and is made thinner.

(second embodiment)

The second embodiment is basically the same as the first embodiment, the same reference numerals as in the first embodiment, and only different points will be described below.

Tables 5 and 6 show design data of the imaging optical lens 20 according to the second embodiment of the present invention.

[ TABLE 5 ]

Table 6 shows aspherical surface data of each lens in the image pickup optical lens 20 according to the second embodiment of the present invention.

[ TABLE 6 ]

Tables 7 and 8 show the inflection points and stagnation point design data of each lens in the imaging optical lens 20 according to the second embodiment of the present invention.

[ TABLE 7 ]

	Number of points of inflection	Position of reverse curvature 1	Position of reverse curvature 2
				P1R1
P1R2
				P2R1
P2R2
				P3R1	2	0.865	1.855
P3R2	2	0.555	1.935
				P4R1	2	0.375	2.015
P4R2
				P5R1
P5R2	1	2.815
				P6R1
P6R2	2	2.255	2.675
				P7R1	2	0.955	3.445
P7R2
				P8R1	2	2.725	4.865
P8R2	1	1.265

[ TABLE 8 ]

	Number of stagnation points	Location of stagnation 1	Location of stagnation 2
				P1R1
P1R2
				P2R1
P2R2
				P3R1	2	1.505	2.055
P3R2	2	0.965	2.285
				P4R1	1	0.635
P4R2
				P5R1
P5R2
				P6R1
P6R2
				P7R1	1	1.605
P7R2
				P8R1	1	4.545
P8R2	1	4.305

Fig. 5 shows an imaging optical lens 20 according to a second embodiment of the present invention.

Fig. 6 and 7 are schematic diagrams showing axial aberrations and chromatic aberration of magnification of light having wavelengths of 656nm, 587nm, 546nm, 486nm, and 436nm passing through the imaging optical lens 20 according to the second embodiment. Fig. 8 is a schematic view showing curvature of field and distortion of light having a wavelength of 546nm after passing through the imaging optical lens 20 according to the second embodiment.

As shown in table 13, the second embodiment satisfies each conditional expression.

In the present embodiment, the imaging optical lens 20 has an entrance pupil diameter of 4.483mm, a full field height of 6.400mm, a diagonal field angle of 72.60 °, and is sufficiently corrected for on-axis and off-axis chromatic aberration and has excellent optical characteristics.

(third embodiment)

The third embodiment is basically the same as the first embodiment, the same reference numerals as in the first embodiment, and only different points will be described below.

Tables 9 and 10 show design data of the imaging optical lens 30 according to the third embodiment of the present invention.

[ TABLE 9 ]

Table 10 shows aspherical surface data of each lens in the imaging optical lens 30 according to the third embodiment of the present invention.

[ TABLE 10 ]

Tables 11 and 12 show the inflection points and the stagnation point design data of each lens in the imaging optical lens 30 according to the third embodiment of the present invention.

[ TABLE 11 ]

	Number of points of inflection	Position of reverse curvature 1	Position of reverse curvature 2
				P1R1
P1R2
				P2R1
P2R2
				P3R1
P3R2	2	0.185	2.155
				P4R1	2	0.265	1.965
P4R2
				P5R1
P5R2
				P6R1
P6R2	1	3.555
				P7R1	2	1.065	3.605
P7R2	2	0.455	1.555
				P8R1	2	2.565	4.575
P8R2	1	1.145

[ TABLE 12 ]

Fig. 9 shows an imaging optical lens 30 according to a third embodiment of the present invention.

Fig. 10 and 11 are schematic diagrams showing axial aberrations and chromatic aberration of magnification of light having wavelengths of 656nm, 587nm, 546nm, 486nm, and 436nm passing through the imaging optical lens 30 according to the third embodiment. Fig. 12 is a schematic view showing curvature of field and distortion of light having a wavelength of 546nm after passing through the imaging optical lens 30 according to the third embodiment.

Table 13 below shows the numerical values corresponding to the respective conditional expressions in the present embodiment, in accordance with the conditional expressions described above. Obviously, the imaging optical system of the present embodiment satisfies the above conditional expressions.

In the present embodiment, the imaging optical lens 30 has an entrance pupil diameter of 4.500mm, a full field image height of 6.400mm, a diagonal field angle of 73.00 °, and excellent optical characteristics, and the imaging optical lens 30 has a wide angle and a slim profile, and its on-axis and off-axis chromatic aberration is sufficiently corrected.

[ TABLE 13 ]

Parameter and condition formula	Example 1	Example 2	Example 3
				f1/f	1.35	0.79	1.35
f2	-12.97	-12.93	-13.54
				(R7+R8)/(R7-R8)	0.90	0.21	0.40
d5/d6	3.84	3.80	14.43
				f	8.494	8.518	8.550
f1	11.437	6.688	11.517
				f3	9.841	3007.453	10.513
f4	35.758	26.629	31.186
				f5	35.296	31.316	27.771
f6	-29.399	-32.797	-30.732
				f7	15.133	9.008	22.649
f8	-5.255	-4.514	-5.846
				f12	51.045	11.846	45.776
Fno	1.90	1.90	1.90

It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific embodiments for practicing the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice.

Claims

1. An imaging optical lens, in order from an object side to an image side, comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens; the first lens element with positive refractive power, the second lens element with negative refractive power, the third lens element with positive refractive power, the fourth lens element with positive refractive power, the fifth lens element with positive refractive power, the sixth lens element with negative refractive power, the seventh lens element with positive refractive power, and the eighth lens element with negative refractive power;

0.78≤f1/f≤1.35；

f2<0mm；

0.20≤(R7+R8)/(R7-R8)≤0.90；

3.80≤d5/d6≤15.00。

2. the imaging optical lens according to claim 1, wherein the seventh lens has a focal length f7 and satisfies the following relationship:

1.05≤f7/f≤3.00。

3. the imaging optical lens of claim 1, wherein a radius of curvature of an object-side surface of the first lens is R1, a radius of curvature of an image-side surface of the first lens is R2, an on-axis thickness of the first lens is d1, and an optical total length of the imaging optical lens is TTL and satisfies the following relationship:

-5.03≤(R1+R2)/(R1-R2)≤-0.71；

0.04≤d1/TTL≤0.15。

4. the imaging optical lens of claim 1, wherein a radius of curvature of an object-side surface of the second lens is R3, a radius of curvature of an image-side surface of the second lens is R4, an on-axis thickness of the second lens is d3, and an optical total length of the imaging optical lens is TTL and satisfies the following relationship:

-3.17≤f2/f≤-1.01；

1.25≤(R3+R4)/(R3-R4)≤6.49；

0.01≤d3/TTL≤0.04。

5. the imaging optical lens of claim 1, wherein the focal length of the third lens is f3, the radius of curvature of the object-side surface of the third lens is R5, the radius of curvature of the image-side surface of the third lens is R6, the total optical length of the imaging optical lens is TTL, and the following relationship is satisfied:

0.58≤f3/f≤529.61；

-2.15≤(R5+R6)/(R5-R6)≤432.12；

0.04≤d5/TTL≤0.19。

6. the image-capturing optical lens unit according to claim 1, wherein the focal length of the fourth lens element is f4, the on-axis thickness of the fourth lens element is d7, the total optical length of the image-capturing optical lens unit is TTL, and the following relationship is satisfied:

1.56≤f4/f≤6.31；

0.02≤d7/TTL≤0.08。

7. the imaging optical lens of claim 1, wherein the focal length of the fifth lens element is f5, the radius of curvature of the object-side surface of the fifth lens element is R9, the radius of curvature of the image-side surface of the fifth lens element is R10, the on-axis thickness of the fifth lens element is d9, the total optical length of the imaging optical lens element is TTL, and the following relationship is satisfied:

1.62≤f5/f≤6.23；

0.99≤(R9+R10)/(R9-R10)≤3.32；

0.04≤d9/TTL≤0.18。

8. the imaging optical lens of claim 1, wherein the focal length of the sixth lens element is f6, the radius of curvature of the object-side surface of the sixth lens element is R11, the radius of curvature of the image-side surface of the sixth lens element is R12, the on-axis thickness of the sixth lens element is d11, the total optical length of the imaging optical lens is TTL, and the following relationship is satisfied:

-7.70≤f6/f≤-2.31；

-14.42≤(R11+R12)/(R11-R12)≤-1.81；

0.01≤d11/TTL≤0.10。

9. the imaging optical lens of claim 1, wherein a radius of curvature of an object-side surface of the seventh lens element is R13, a radius of curvature of an image-side surface of the seventh lens element is R14, an on-axis thickness of the seventh lens element is d13, and an optical total length of the imaging optical lens is TTL and satisfies the following relationship:

0.09≤(R13+R14)/(R13-R14)≤0.48；

0.05≤d13/TTL≤0.25。

10. the imaging optical lens of claim 1, wherein the focal length of the eighth lens element is f8, the radius of curvature of the object-side surface of the eighth lens element is R15, the radius of curvature of the image-side surface of the eighth lens element is R16, the on-axis thickness of the eighth lens element is d15, the total optical length of the imaging optical lens is TTL, and the following relationship is satisfied:

-1.37≤f8/f≤-0.35；

0.06≤(R15+R16)/(R15-R16)≤1.03；

0.02≤d15/TTL≤0.11。