CN111077650B

CN111077650B - Image pickup optical lens

Info

Publication number: CN111077650B
Application number: CN201911338344.2A
Authority: CN
Inventors: 林家正
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: 2021-10-08
Anticipated expiration: 2039-12-23
Also published as: CN111077650A

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: f4/f is not less than 4.00 and not more than-1.80; less than or equal to 15.00 (R5+ R6)/(R5-R6) less than or equal to 1.80; d3/d4 is more than or equal to 2.50 and less than or equal to 8.50. The imaging optical lens of the invention has good optical performance such as wide angle, ultrathin 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 with a good function, a light weight, a small size, and a light weight, and thus, 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, the eight-piece lens structure gradually appears in the design of the lens. It is urgently required to provide a wide-angle, ultra-thin optical imaging lens having good optical performance.

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 wide angle and a thin profile 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 image pickup optical lens is f, the focal length of the fourth lens is f4, 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 on-axis thickness of the second lens is d3, and the on-axis distance from the image side surface of the second lens to the object side surface of the third lens is d4, so that the following relational expressions are satisfied:

-4.00≤f4/f≤-1.80；

-15.00≤(R5+R6)/(R5-R6)≤-1.80；

2.50≤d3/d4≤8.50。

preferably, the radius of curvature of the object-side surface of the first lens is R1, the radius of curvature of the image-side surface of the first lens is R2, and the following relation is satisfied:

-6.00≤(R1+R2)/(R1-R2)≤-2.30。

preferably, the focal length of the first lens is f1, and the following relation is satisfied:

1.06≤f1/f≤1.90。

preferably, and the on-axis thickness of the first lens is d1, the total optical length of the image pickup optical lens is TTL, and the following relationship is satisfied: and satisfies the following relationships:

0.04≤d1/TTL≤0.14。

preferably, the focal length of the second lens element is f2, the radius of curvature of the object-side surface of the second lens element is R3, the radius of curvature of the image-side surface of the second lens element is R4, and the on-axis thickness of the second lens element is d3, the total optical length of the image pickup optical lens is TTL, and the following relationships are satisfied:

--13.54≤f2/f≤2.57；

-3.72≤(R3+R4)/(R3-R4)≤8.15；

0.02≤d3/TTL≤0.07。

preferably, the focal length of the third lens is f3, the on-axis thickness of the third lens is d5, the total optical length of the imaging optical lens is TTL, and the following relation is satisfied:

2.36≤f3/f≤64.67；

0.02≤d5/TTL≤0.07。

preferably, a curvature radius of an object-side surface of the fourth lens element is R7, a curvature radius of an image-side surface of the fourth lens element is R8, and an on-axis thickness of the fourth lens element is d7, an optical total length of the imaging optical lens system is TTL, and the following relationship is satisfied:

-0.76≤(R7+R8)/(R7-R8)≤0.76；

0.02≤d7/TTL≤0.06。

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, and the on-axis thickness of the fifth lens element is d9, the total optical length of the image pickup optical lens is TTL, and the following relationships are satisfied:

-28.91≤f5/f≤277.84；

-260.90≤(R9+R10)/(R9-R10)≤16.41；

0.02≤d9/TTL≤0.07。

preferably, 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 system is TTL, and the following relationships are satisfied:

-7.15≤f6/f≤391.80；

-134.38≤(R11+R12)/(R11-R12)≤4.60；

0.03≤d11/TTL≤0.09。

preferably, the focal length of the seventh lens element is f7, the on-axis radius of curvature of the object-side surface of the seventh lens element is R13, the on-axis radius of curvature of the image-side surface of the seventh lens element is R14, and the total optical length of the imaging optical lens system is TTL and satisfies the following relationship:

0.54≤f7/f≤2.39；

-6.07≤(R13+R14)/(R13-R14)≤-1.24；

0.04≤d13/TTL≤0.12。

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, and 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:

-1.39≤f8/f≤-0.45；

-1.83≤(R15+R16)/(R15-R16)≤-0.58；

0.03≤d15/TTL≤0.10。

the invention has the beneficial effects that: the imaging optical lens according to the present invention has excellent optical characteristics, satisfies the requirements of wide angle and thinness, and is particularly suitable for a mobile phone imaging lens assembly and a WEB imaging lens which are composed of high-pixel imaging elements such as 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.

Fig. 13 is a schematic configuration diagram of an imaging optical lens according to a fourth embodiment of the present invention;

fig. 14 is a schematic view of axial aberrations of the image pickup optical lens shown in fig. 13;

fig. 15 is a schematic diagram of chromatic aberration of magnification of the imaging optical lens shown in fig. 13;

fig. 16 is a schematic view of curvature of field and distortion of the imaging optical lens shown in fig. 13.

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 f of the whole imaging optical lens 10 and the focal length f4 of the fourth lens L4, the following relation is satisfied: f4/f is 4.00-1.80, and the ratio of the focal length of the fourth lens L4 to the overall focal length is defined. When the optical power is within the specified range, the system has better imaging quality and lower sensitivity through reasonable distribution of the optical power. Preferably, it satisfies-3.93. ltoreq. f 4/f. ltoreq-1.82.

The radius of curvature of the object-side surface of the third lens L3 is R5, and the radius of curvature of the image-side surface of the third lens L3 is R6, -15.00 ≦ (R5+ R6)/(R5-R6) ≦ -1.80, and the shape of the third lens L3 is defined, and in this range, it is advantageous to correct the off-axis aberration with the development of an extremely thin and wide angle. Preferably, it satisfies-14.99 ≦ (R5+ R6)/(R5-R6) ≦ -1.85.

Defining an on-axis thickness of the second lens as d3, an on-axis distance of an image-side surface of the second lens to an object-side surface of the third lens as d4, satisfying the following relationship: d3/d4 is more than or equal to 2.50 and less than or equal to 8.50, the ratio of the thickness of the second lens to the air space of the second and third lenses is specified, and the total length of the optical system is favorably compressed within the range of conditional expressions, so that the ultrathin effect is realized. Satisfies d3/d4 of 2.55-8.28.

The curvature radius of the object side surface of the first lens L1 is R1, the curvature radius of the image side surface of the first lens L1 is R2, -6.00 ≦ (R1+ R2)/(R1-R2) ≦ -2.30, the shape of the first lens is defined, and the deflection degree of light rays passing through the lens can be alleviated and the aberration can be effectively reduced within the range defined by the conditional expression. Preferably, it satisfies-5.95 ≦ (R1+ R2)/(R1-R2) ≦ -2.32.

Defining the focal length f of the entire image pickup optical lens 10 and the focal length f1 of the first lens L1, the following relations are satisfied: f1/f is more than or equal to 1.06 and less than or equal to 1.90, the ratio of the focal length of the first lens to the total focal length of the system is specified, and the spherical aberration and the field curvature of the system can be effectively balanced.

When the focal length of the image pickup optical lens 10, the focal length of each lens, the on-axis distance from the image side surface to the object side surface of the relevant lens, and the on-axis thickness satisfy the above relation, the image pickup optical lens 10 can have high performance, and meet the design requirements of large aperture, wide angle, and ultra-thin.

The on-axis thickness of the first lens L1 is d1, the total optical length of the shooting optical lens is TTL, and the following relational expression is satisfied: d1/TTL is more than or equal to 0.04 and less than or equal to 0.14, and ultra-thinning is favorably realized within the range specified by the conditional expression. Preferably, 0.06. ltoreq. d 1/TTL. ltoreq.0.12 is satisfied.

The focal length of the second lens L2 is f2, and the series relation is satisfied: 13.54 ≦ f2/f ≦ 2.57, and the ratio of the focal length of the second lens to the total focal length of the system is specified within the conditional expression range, so that the system has better imaging quality and lower sensitivity through reasonable distribution of the focal lengths. Preferably, it satisfies-8.46. ltoreq. f 2/f. ltoreq.2.06.

The curvature radius of the object side surface of the second lens L2 is R3, the curvature radius of the image side surface of the second lens L2 is R4, -3.72 (R3+ R4)/(R3-R4) is less than or equal to 8.15, the shape of the second lens L2 is defined, and the chromatic aberration of the axis can be corrected favorably as the lens is changed to an ultra-thin wide angle within the range. Preferably, it satisfies-2.32 ≦ (R3+ R4)/(R3-R4). ltoreq.6.52.

The on-axis thickness of the second lens L2 is d3, the total optical length of the shooting optical lens is TTL, and the following relational expression is satisfied: d3/TTL is more than or equal to 0.02 and less than or equal to 0.07, and ultra-thinning is facilitated. Preferably, 0.03. ltoreq. d 3/TTL. ltoreq.0.06 is satisfied.

Defining the focal length f of the entire image pickup optical lens 10 and the focal length f3 of the third lens L3, the following relations are satisfied: f3/f 64.67 is more than or equal to 2.36, the ratio of the focal length of the third lens to the total focal length of the system is regulated, and the system has better imaging quality and lower sensitivity through reasonable distribution of the focal lengths. Preferably, 3.77 ≦ f3/f ≦ 51.74.

The on-axis thickness of the third lens L3 is d5, the total optical length of the shooting optical lens is TTL, and the following relational expression is satisfied: d5/TTL is more than or equal to 0.02 and less than or equal to 0.07, and the ultra-thinning is favorably realized within the specified range of the conditional expression. Preferably, 0.04. ltoreq. d 5/TTL. ltoreq.0.06 is satisfied.

The curvature radius of the object side surface of the fourth lens L4 is R7, the curvature radius of the image side surface of the fourth lens L4 is R8, -0.76 ≦ (R7+ R8)/(R7-R8) ≦ 0.76, and the shape of the fourth lens L4 is defined, so that it is advantageous to correct the problems such as the aberration of the off-axis angle with the development of the ultra-thin and wide-angle in the conditional expression range. Preferably, it satisfies-0.48 ≦ (R7+ R8)/(R7-R8). ltoreq.0.61.

The on-axis thickness of the fourth lens L4 is d7, the total optical length of the shooting optical lens is TTL, and the following relational expression is satisfied: d7/TTL is more than or equal to 0.02 and less than or equal to 0.06, and ultra-thinning is facilitated. Preferably, 0.03. ltoreq. d 7/TTL. ltoreq.0.05 is satisfied.

The focal length of the fifth lens L5 is f5, and the series relation is satisfied: 28.91 ≦ f5/f ≦ 277.84, and the ratio of the focal length of the fifth lens to the total focal length of the system is specified within the conditional expression, so that the system has better imaging quality and lower sensitivity through reasonable distribution of the focal lengths. Preferably, it satisfies-18.07. ltoreq. f 5/f. ltoreq. 222.27.

The curvature radius of the object side surface of the fifth lens L5 is R9, the curvature radius of the image side surface of the fifth lens L5 is R10, -260.90 (R9+ R10)/(R9-R10) is 16.41 or less, the shape of the fifth lens L5 is defined, and when the condition is within the range of the conditional expression, the problem of aberration of the off-axis angle and the like can be favorably corrected along with the development of the ultra-thin and wide-angle. Preferably, it satisfies-163.06 ≦ (R9+ R10)/(R9-R10). ltoreq.13.13.

The on-axis thickness of the fifth lens L5 is d9, the total optical length of the shooting optical lens is TTL, and the following relational expression is satisfied: d9/TTL is more than or equal to 0.02 and less than or equal to 0.07, and ultra-thinning is favorably realized within the range of conditional expressions. Preferably, 0.03. ltoreq. d 9/TTL. ltoreq.0.05 is satisfied.

The focal length of the sixth lens L6 is f6, and the series relation is satisfied: 7.15 ≦ f6/f ≦ 391.80, which specifies the ratio of the focal length of the sixth lens L6 to the overall focal length. When in the specified range, the system has better imaging quality and lower sensitivity. Preferably, it satisfies-4.47. ltoreq. f 6/f. ltoreq. 313.44.

The curvature radius of the object side surface of the sixth lens L6 is R11, the curvature radius of the image side surface of the sixth lens L6 is R12, -134.38 ≤ (R11+ R12)/(R11-R12) ≤ 4.60, and the shape of the sixth lens L6 is defined, so that the problem of aberration of the off-axis angle can be corrected with the development of a thin and wide angle within the conditional expression. Preferably, it satisfies-83.99 ≦ (R11+ R12)/(R11-R12). ltoreq.3.68.

The on-axis thickness of the sixth lens L6 is d11, the total optical length of the imaging optical lens is TTL, and the following relational expression is satisfied: d11/TTL is more than or equal to 0.03 and less than or equal to 0.09, and ultra-thinning is facilitated. Preferably, 0.04. ltoreq. d 11/TTL. ltoreq.0.07 is satisfied.

The focal length of the seventh lens L7 is f7, and the series relation is satisfied: f7/f is more than or equal to 0.54 and less than or equal to 2.39, the ratio of the focal length of the seventh lens 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, 0.86. ltoreq. f 7/f. ltoreq.1.91 is satisfied.

The curvature radius R13 of the object side surface of the seventh lens L7 and the curvature radius R14 of the image side surface of the seventh lens L7 are defined, and the following relations are satisfied: the shape of the seventh lens L7 is defined to be (R13+ R14)/(R13-R14) to be (1.83) or more and (1.24) or less, and the problem of aberration of an off-axis picture angle is favorably corrected as the ultra-thin wide angle is developed within a condition range. Preferably, it satisfies-3.80 ≦ (R13+ R14)/(R13-R14) ≦ -1.55.

The on-axis thickness of the seventh lens L7 is d13, the total optical length of the imaging optical lens is TTL, and the following relational expression is satisfied: d13/TTL is more than or equal to 0.04 and less than or equal to 0.12, and ultra-thinning is facilitated. Preferably, 0.06. ltoreq. d 13/TTL. ltoreq.0.10 is satisfied.

The focal length of the eighth lens L8 is f8, and the series relation is satisfied: f8/f is less than or equal to-0.45, the ratio of the focal length of the eighth lens 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 lengths. Preferably, it satisfies-0.87. ltoreq. f 8/f. ltoreq-0.57.

The curvature radius of the object side surface of the eighth lens L8 is R15, the curvature radius of the image side surface of the eighth lens L8 is R16, the value of (R15+ R16)/(R15-R16) is not more than-0.58, the shape of the eighth lens L8 is defined, and problems such as off-axis angularity and the like are favorably corrected as the ultra-thin wide angle is increased within a condition range. Preferably, it satisfies-1.14 ≦ (R15+ R16)/(R15-R16). ltoreq.0.73.

The on-axis thickness of the eighth lens L8 is d15, the total optical length of the shooting optical lens is TTL, and the following relational expression is satisfied: d15/TTL is more than or equal to 0.03 and less than or equal to 0.10, and ultra-thinning is facilitated. Preferably, 0.05. ltoreq. d 15/TTL. ltoreq.0.08 is satisfied.

In the present embodiment, the ratio TTL/IH of the total optical length TTL to the image height of the image pickup optical lens 10 is less than or equal to 1.21, which is beneficial to achieving ultra-thinning.

In the present embodiment, the F-number (Fno) of the imaging optical lens 10 is 1.96 or less. The large aperture is large, and the imaging performance is good.

In the present embodiment, the field angle FOV of the imaging optical lens 10 is equal to or greater than 85 °, which is advantageous for achieving a wide angle.

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.

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 unit of focal length, on-axis distance, curvature radius, on-axis thickness, position of reverse curvature and position of stagnation point is mm.

TTL: optical length (on-axis distance from the object side surface of the 1 st lens L1 to the image forming surface) in mm;

preferably, the object side surface and/or the image side surface of the lens may be further provided with an inflection point and/or a stagnation point to meet the requirement of high-quality imaging.

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 on-axis distance from the image side surface of the optical filter GF to the image surface;

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;

v8: 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. 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, and P7R1 and P7R2 represent the object-side surface and the image-side surface of the seventh lens L7, respectively. 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 image pickup 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 ]

	Number of points of inflection	Position of reverse curvature 1	Position of reverse curvature 2	Position of reverse curvature 3
					P1R1	0
P1R2	1	1.625
					P2R1	0
P2R2	1	1.645
					P3R1	2	1.465	1.705
P3R2	1	0.675
					P4R1	0
P4R2	2	1.115	1.825
					P5R1	1	0.545
P5R2	2	0.605	2.285
					P6R1	2	0.685	2.815
P6R2	0
					P7R1	1	1.165
P7R2	3	1.205	3.635	4.285
					P8R1	1	2.825
P8R2	2	0.335	5.835

[ TABLE 4 ]

	Number of stagnation points	Location of stagnation 1	Location of stagnation 2
				P1R1	0
P1R2	0
				P2R1	0
P2R2	0
				P3R1	0
P3R2	1	1.055
				P4R1	0
P4R2	2	1.665	1.915
				P5R1	1	0.955
P5R2	1	1.045
				P6R1	1	0.995
P6R2	0
				P7R1	1	2.095
P7R2	1	2.005
				P8R1	0
P8R2	1	0.575

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 the field curvature S in fig. 4 is the field curvature in the sagittal direction, and T is the field curvature in the tangential direction.

Table 17 shown later shows values corresponding to the parameters specified in the conditional expressions for the respective numerical values in examples 1, 2, 3, and 4.

As shown in table 17, the first embodiment satisfies each conditional expression.

In the present embodiment, the imaging optical lens has an entrance pupil diameter of 4.332mm, a full field image height of 8.00mm, a diagonal field angle of 85.60 °, a large aperture, a wide angle, and a high profile, and has excellent optical characteristics with on-axis and off-axis chromatic aberration sufficiently corrected.

(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 imaging optical lens 20 according to the second embodiment of the present invention.

[ TABLE 6 ]

Tables 7 and 8 show the inflection point 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	Position of reverse curvature 3
					P1R1	0
P1R2	2	1.435	1.735
					P2R1	3	1.225	1.615	2.015
P2R2	1	1.675
					P3R1	1	1.295
P3R2	1	0.615
					P4R1	3	0.695	1.065	1.645
P4R2	0
					P5R1	1	0.525
P5R2	2	0.515	2.245
					P6R1	2	0.595	2.755
P6R2	1	0.335
					P7R1	3	1.155	3.505	3.725
P7R2	3	1.205	3.665	4.235
					P8R1	1	2.835
P8R2	2	0.375	5.755

[ TABLE 8 ]

	Number of stagnation points	Location of stagnation 1
			P1R1	0
P1R2	0
			P2R1	0
P2R2	1	1.955
			P3R1	1	1.775
P3R2	1	0.955
			P4R1	1	1.885
P4R2	0
			P5R1	1	0.905
P5R2	1	0.875
			P6R1	1	0.975
P6R2	1	0.575
			P7R1	1	2.055
P7R2	1	2.005
			P8R1	0
P8R2	1	0.655

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 17, the second embodiment satisfies each conditional expression.

In the present embodiment, the imaging optical lens has an entrance pupil diameter of 4.358mm, a full field image height of 8.00mm, a diagonal field angle of 85.20 °, a large aperture, a wide angle, and a high profile, and has excellent optical characteristics with on-axis and off-axis chromatic aberration sufficiently corrected.

(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	Position of reverse curvature 3
					P1R1	0
P1R2	2	1.305	1.995
					P2R1	1	1.035
P2R2	1	0.805
					P3R1	1	1.645
P3R2	1	0.535
					P4R1	3	0.675	1.295	1.605
P4R2	0
					P5R1	1	0.525
P5R2	2	0.475	2.215
					P6R1	2	0.545	2.885
P6R2	1	0.515
					P7R1	1	1.155
P7R2	1	1.245
					P8R1	1	2.805
P8R2	2	0.315	5.665

[ TABLE 12 ]

	Number of stagnation points	Location of stagnation 1
			P1R1	0
P1R2	0
			P2R1	1	1.735
P2R2	1	1.195
			P3R1	0
P3R2	1	0.945
			P4R1	1	1.785
P4R2	0
			P5R1	1	0.885
P5R2	1	0.835
			P6R1	1	1.045
P6R2	1	1.005
			P7R1	1	2.125
P7R2	1	1.985
			P8R1	0
P8R2	1	0.545

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

In the present embodiment, the imaging optical lens has an entrance pupil diameter of 4.375mm, a full field image height of 8.00mm, a diagonal field angle of 85.20 °, a large aperture, a wide angle, and a high profile, and has excellent optical characteristics with a sufficiently corrected on-axis and off-axis chromatic aberration.

(fourth embodiment)

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

Tables 13 and 14 show design data of the imaging optical lens 40 according to the fourth embodiment of the present invention.

[ TABLE 13 ]

Table 14 shows aspherical surface data of each lens in the imaging optical lens 40 according to the fourth embodiment of the present invention.

[ TABLE 14 ]

Tables 15 and 16 show the inflection points and the stagnation point design data of each lens in the imaging optical lens 40 according to the fourth embodiment of the present invention.

[ TABLE 15 ]

	Number of points of inflection	Position of reverse curvature 1	Position of reverse curvature 2	Position of reverse curvature 3
					P1R1	0
P1R2	2	1.305	2.005
					P2R1	1	1.035
P2R2	1	0.815
					P3R1	1	1.655
P3R2	1	0.545
					P4R1	3	0.675	1.295	1.605
P4R2	0
					P5R1	1	0.525
P5R2	2	0.485	2.215
					P6R1	2	0.535	2.885
P6R2	1	0.515
					P7R1	1	1.155
P7R2	1	1.245
					P8R1	1	2.805
P8R2	2	0.315	5.655

[ TABLE 16 ]

	Number of stagnation points	Location of stagnation 1
			P1R1	0
P1R2	0
			P2R1	1	1.745
P2R2	1	1.225
			P3R1	0
P3R2	1	0.965
			P4R1	1	1.795
P4R2	0
			P5R1	1	0.895
P5R2	1	0.845
			P6R1	1	1.035
P6R2	1	0.995
			P7R1	1	2.125
P7R2	1	1.995
			P8R1	0
P8R2	1	0.535

Fig. 14 and 15 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 40 according to the fourth embodiment. Fig. 16 is a schematic view showing curvature of field and distortion of light having a wavelength of 546nm after passing through the imaging optical lens 40 according to the fourth embodiment.

As shown in table 17, the fourth embodiment satisfies each conditional expression.

In the present embodiment, the imaging optical lens has an entrance pupil diameter of 4.392mm, a full field image height of 8.00mm, a diagonal field angle of 85.20 °, a large aperture, a wide angle, and a high profile, and has excellent optical characteristics with on-axis and off-axis chromatic aberration sufficiently corrected.

[ TABLE 17 ]

Parameter and condition formula	Example 1	Example 2	Example 3	Example 4
					f4/f	-3.85	-1.85	-1.95	-1.96
(R5+R6)/(R5-R6)	-1.89	-1.90	-9.00	-14.99
					d3/d4	2.60	7.25	8.06	8.04
f	8.447	8.498	8.531	8.565
					f1	8.975	16.125	14.373	14.369
f2	-57.201	14.557	12.480	12.303
					f3	45.426	40.048	230.518	369.274
f4	-32.536	-15.700	-16.644	-16.759
					f5	-122.084	1574.063	1130.219	904.061
f6	93.278	2219.695	-30.481	-29.886
					f7	12.681	13.524	9.163	9.165
f8	-5.799	-5.897	-5.809	-5.818
					f12	10.241	8.067	7.100	7.049
Fno	1.95	1.95	1.95	1.95

In table 17, f12 is the combined focal length of the first lens L1 and the second lens L2.

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, comprising eight lens elements in total, in order from an object side to an image side: a first lens element with positive refractive power, a second lens element with positive refractive power, a third lens element with positive refractive power, a fourth lens element with negative refractive power, a fifth lens element with negative refractive power, a sixth lens element with positive refractive power, a seventh lens element with positive refractive power, and an eighth lens element with negative refractive power;

the object side surface of the first lens is a convex surface at the paraxial position, and the image side surface of the first lens is a concave surface at the paraxial position; the object side surface of the second lens is convex at the paraxial part; the object side surface of the third lens is a convex surface at the paraxial position, and the image side surface of the third lens is a concave surface at the paraxial position; the object side surface of the fourth lens is a concave surface at the paraxial position, and the image side surface of the fourth lens is a concave surface at the paraxial position; the object side surface of the fifth lens is a convex surface at the paraxial position, and the image side surface of the fifth lens is a concave surface at the paraxial position; the object side surface of the sixth lens is convex at the paraxial part; the object side surface of the seventh lens is a convex surface at the paraxial region, and the image side surface and the paraxial region of the seventh lens are concave surfaces; the object side surface of the eighth lens is concave at the paraxial region, and the image side surface of the eighth lens is concave at the paraxial region;

-4.00≤f4/f≤-1.80；

-15.00≤(R5+R6)/(R5-R6)≤-1.80；

2.50≤d3/d4≤8.50。

2. the imaging optical lens of claim 1, wherein the radius of curvature of the object-side surface of the first lens is R1, the radius of curvature of the image-side surface of the first lens is R2, and the following relationship is satisfied:

-6.00≤(R1+R2)/(R1-R2)≤-2.30。

3. the imaging optical lens according to claim 1, wherein the first lens has a focal length f1 and satisfies the following relationship:

1.06≤f1/f≤1.90。

4. a photographic optical lens according to claim 1, characterized in that the on-axis thickness of the first lens is d1, the total optical length of the photographic optical lens is TTL, and the following relation is satisfied: and satisfies the following relationships:

0.04≤d1/TTL≤0.14。

5. the imaging optical lens of claim 1, wherein the focal length of the second lens is f2, the radius of curvature of the object-side surface of the second lens is R3, the radius of curvature of the image-side surface of the second lens is R4, and the on-axis thickness of the second lens is d3, the total optical length of the imaging optical lens is TTL, and the following relationship is satisfied:

-13.54≤f2/f≤2.57；

-3.72≤(R3+R4)/(R3-R4)≤8.15；

0.02≤d3/TTL≤0.07。

6. the image-capturing optical lens according to claim 1, wherein the third lens has a focal length f3 and an on-axis thickness d5, the image-capturing optical lens has a total optical length TTL, and satisfies the following relationship:

2.36≤f3/f≤64.67；

0.02≤d5/TTL≤0.07。

7. the image-capturing optical lens unit according to claim 1, wherein the radius of curvature of the object-side surface of the fourth lens element is R7, the radius of curvature of the image-side surface of the fourth lens element is R8, and the on-axis thickness of the fourth lens element is d7, the image-capturing optical lens unit has a total optical length TTL, and satisfies the following relationship:

-0.76≤(R7+R8)/(R7-R8)≤0.76；

0.02≤d7/TTL≤0.06。

8. the image-capturing optical lens unit according to 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, and the on-axis thickness of the fifth lens element is d9, the optical total length of the image-capturing optical lens unit is TTL, and the following relationship is satisfied:

-28.91≤f5/f≤277.84；

-260.90≤(R9+R10)/(R9-R10)≤16.41；

0.02≤d9/TTL≤0.07。

9. the image-capturing optical lens unit according to claim 1, wherein the sixth lens element has a focal length f6, a radius of curvature of an object-side surface of the sixth lens element is R11, a radius of curvature of an image-side surface of the sixth lens element is R12, an on-axis thickness of the sixth lens element is d11, an optical total length of the image-capturing optical lens unit is TTL, and the following relationship is satisfied:

-7.15≤f6/f≤391.80；

-134.38≤(R11+R12)/(R11-R12)≤4.60；

0.03≤d11/TTL≤0.09。

10. the image-capturing optical lens unit according to claim 1, wherein the seventh lens element has a focal length f7, an on-axis radius of curvature of the object-side surface of the seventh lens element is R13, an on-axis radius of curvature of the image-side surface of the seventh lens element is R14, and the image-capturing optical lens unit has a total optical length TTL and satisfies the following relationship:

0.54≤f7/f≤2.39；

-6.07≤(R13+R14)/(R13-R14)≤-1.24；

0.04≤d13/TTL≤0.12。

11. the image-taking optical lens according to claim 1, wherein the eighth lens element has a focal length f8, a radius of curvature of an object-side surface of the eighth lens element is R15, a radius of curvature of an image-side surface of the eighth lens element is R16, and an on-axis thickness d15, and the image-taking optical lens has an optical total length TTL satisfying the following relationship:

-1.39≤f8/f≤-0.45；

-1.83≤(R15+R16)/(R15-R16)≤-0.58；

0.03≤d15/TTL≤0.10。