CN111007653B

CN111007653B - Image pickup optical lens

Info

Publication number: CN111007653B
Application number: CN201911385186.6A
Authority: CN
Inventors: 朱军彦
Original assignee: Chengrui Optics Changzhou Co Ltd
Current assignee: Chengrui Optics Changzhou Co Ltd
Priority date: 2019-12-28
Filing date: 2019-12-28
Publication date: 2021-09-24
Anticipated expiration: 2039-12-28
Also published as: CN111007653A

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 is more than or equal to 0.00; f2/f is more than or equal to 0.50 and less than or equal to 1.05; n3 is more than or equal to 1.55 and less than or equal to 1.70; d1/d2 is more than or equal to 2.50 and less than or equal to 3.50; the ratio of (R1+ R2)/(R1-R2) is more than or equal to-20.00 and less than or equal to-1.50. The imaging optical lens has excellent optical characteristics and meets the requirements of ultra-thinness and wide angle.

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, 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 ultra-thinning and 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 image pickup optical lens is f, the focal length of the second lens is f2, the refractive index of the third lens is n3, the on-axis thickness of the first lens is d1, the on-axis distance from the image side surface of the first lens to the object side surface of the second lens is d2, the curvature radius of the object side surface of the first lens is R1, and the curvature radius of the image side surface of the first lens is R2, so that the following relational expression is satisfied:

f1≥0.00；

0.50≤f2/f≤1.05；

1.55≤n3≤1.70；

2.50≤d1/d2≤3.50；

-20.00≤(R1+R2)/(R1-R2)≤-1.50。

preferably, the focal length of the sixth lens is f6, and the following relation is satisfied:

-4.50≤f6/f≤-2.00。

preferably, the focal length of the first lens is f1, the on-axis thickness of the first lens is d1, the total optical length of the imaging optical lens is TTL, and the following relation is satisfied:

1.49≤f1/f≤8.75；

0.01≤d1/TTL≤0.06。

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:

-0.24≤(R3+R4)/(R3-R4)≤0.58

0.03≤d3/TTL≤0.11。

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, the on-axis thickness of the third lens element is d5, and the total optical length of the imaging optical lens system is TTL and satisfies the following relationships:

-25.77≤f3/f≤-0.53；

-0.05≤(R5+R6)/(R5-R6)≤14.22；

0.02≤d5/TTL≤0.10。

preferably, the focal length of the fourth lens element is f4, 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, the on-axis thickness of the fourth lens element is d7, the total optical length of the image pickup optical lens is TTL, and the following relationships are satisfied:

-3.27≤f4/f≤-0.86；

0.77≤(R7+R8)/(R7-R8)≤3.01；

0.01≤d7/TTL≤0.04。

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:

0.83≤f5/f≤3.47；

-1.25≤(R9+R10)/(R9-R10)≤-0.10；

0.03≤d9/TTL≤0.10。

preferably, 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, and the total optical length of the imaging optical lens system is TTL and satisfies the following relationship:

-2.45≤(R11+R12)/(R11-R12)≤-0.02；

0.03≤d11/TTL≤0.15。

preferably, the focal length of the seventh lens element is f7, the curvature radius of the object-side surface of the seventh lens element is R13, the curvature radius of the image-side surface of the seventh lens element is R14, the on-axis thickness of the seventh lens element is d13, the total optical length of the imaging optical lens system is TTL, and the following relationships are satisfied:

0.51≤f7/f≤1.72；

-0.51≤(R13+R14)/(R13-R14)≤0.30；

0.08≤d13/TTL≤0.36。

preferably, 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, and the total optical length of the imaging optical lens system is TTL and satisfies the following relationships:

-1.40≤f8/f≤-0.42；

0.13≤(R15+R16)/(R15-R16)≤0.72；

0.03≤d15/TTL≤0.17。

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

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: a first lens L1, a second lens L2, a stop S1, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an 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.

The focal length of the first lens L1 is f1, f1 is more than or equal to 0, the positive and negative of the focal length of the first lens are regulated, and the system has better imaging quality and lower sensitivity through reasonable distribution of the focal length.

The focal length of the whole shooting optical lens 10 is defined as f, the focal length of the second lens L2 is defined as f2, f2/f is more than or equal to 0.50 and less than or equal to 1.05, and the spherical aberration and the field curvature of the system can be effectively balanced through reasonable distribution of the focal power.

The refractive index of the third lens L3 is defined as n3, 1.55 is not less than n3 is not more than 1.70, the refractive index of the third lens is regulated, and the improvement of the optical system performance is facilitated within the conditional expression range. Preferably, 1.56. ltoreq. n 3. ltoreq.1.69 is satisfied.

The on-axis thickness of the first lens L1 is defined as d1, the on-axis distance from the image side surface of the first lens L1 to the object side surface of the second lens L2 is defined as d2, d1/d2 is defined as 2.50-3.50, the ratio of the thickness of the first lens to the air interval of the first and second lenses is defined, and the optical system is favorably compressed in total length and achieves the ultrathin effect within the conditional expression range.

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, -20.00 ≦ (R1+ R2)/(R1-R2) ≦ -1.50, and the shape of the first lens is defined, so that the deflection degree of light rays passing through the lens can be alleviated within the range defined by the conditional expression, and the aberration can be effectively reduced.

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 relational expressions, the image pickup optical lens 10 can have excellent optical characteristics, and can satisfy the requirements of ultra-thinning and wide angle, and is particularly suitable for a mobile phone image pickup lens assembly and a WEB image pickup lens which are composed of image pickup elements such as a CCD and a CMOS for high pixel.

Defining the focal length of the sixth lens to be f6, -4.50 ≤ f6/f ≤ 2.00, and defining the ratio of the focal length of the sixth lens to the total focal length of the system, so that the system has better imaging quality and lower sensitivity through reasonable distribution of the focal lengths.

The focal length of the first lens L1 is f1, f1/f is more than or equal to 1.49 and less than or equal to 8.75, and the ratio of the focal length of the first lens L1 to the overall focal length is specified. When the first lens element is within the specified range, the first lens element has proper positive refractive power, which is beneficial to reducing system aberration and is beneficial to the development of ultra-thinning and wide-angle lens. Preferably, 2.38. ltoreq. f 1/f. ltoreq.7.00 is satisfied.

The on-axis thickness of the first lens L1 is d1, the total optical length of the imaging optical lens is TTL, and the following relational expression is satisfied: d1/TTL is more than or equal to 0.01 and less than or equal to 0.06, and ultra-thinning is facilitated. Preferably, 0.02. ltoreq. d 1/TTL. ltoreq.0.05 is satisfied.

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, and the following relational expression is satisfied: the shape of the second lens L2 is defined to be 0.24-0.58 (R3+ R4)/(R3-R4), and the problem of chromatic aberration on the axis can be corrected favorably as the lens is brought to a super-thin wide angle in the range. Preferably, it satisfies-0.15. ltoreq. (R3+ R4)/(R3-R4). ltoreq.0.46.

The on-axis thickness of the second lens L2 is d3, and satisfies the following relation: d3/TTL is more than or equal to 0.03 and less than or equal to 0.11, and ultra-thinning is facilitated. Preferably, 0.04. ltoreq. d 3/TTL. ltoreq.0.09 is satisfied.

The third lens L3 has a focal length f3 and satisfies the following relationship: -25.77 ≦ f3/f ≦ -0.53, allowing better imaging quality and lower sensitivity of the system through reasonable distribution of optical power. Preferably, it satisfies-16.11. ltoreq. f 3/f. ltoreq-0.66.

The curvature radius of the object side surface of the third lens L3 is R5, the curvature radius of the image side surface of the third lens L3 is R6, and the following relations are satisfied: 0.05-14.22 of (R5+ R6)/(R5-R6), can effectively control the shape of the third lens L3, is beneficial to the formation of the third lens L3, and can alleviate the deflection degree of light rays passing through the lens within the range specified by the conditional expression, thereby effectively reducing aberration. Preferably, it satisfies-0.03 ≦ (R5+ R6)/(R5-R6). ltoreq.11.38.

The on-axis thickness of the third lens L3 is d5, and satisfies the following relation: d5/TTL is more than or equal to 0.02 and less than or equal to 0.10, and ultra-thinning is facilitated. Preferably, 0.03. ltoreq. d 5/TTL. ltoreq.0.08 is satisfied.

The focal length of the fourth lens L4 is f4, and the following relationship is satisfied: 3.27 ≦ f4/f ≦ -0.86, allowing better imaging quality and lower sensitivity of the system through reasonable distribution of optical power. Preferably, it satisfies-2.04. ltoreq. f 4/f. ltoreq-1.08.

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, and the following relational expression is satisfied: 0.77 ≦ (R7+ R8)/(R7-R8) ≦ 3.01, and the shape of the fourth lens L4 is defined, and when the shape is within the range, it is advantageous to correct the aberration of the off-axis angle and the like with the development of an ultra-thin wide angle. Preferably, 1.23 ≦ (R7+ R8)/(R7-R8) ≦ 2.40.

The on-axis thickness of the fourth lens L4 is d7, and the following relation is satisfied: d7/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, 0.02. ltoreq. d 7/TTL. ltoreq.0.03 is satisfied.

The focal length of the entire image pickup optical lens 10 is f, and the focal length of the fifth lens L5 is f5, and the following relations are satisfied: f5/f is more than or equal to 0.83 and less than or equal to 3.47, and the definition of the fifth lens L5 can effectively make the light ray angle of the camera lens smooth and reduce the tolerance sensitivity. Preferably, 1.33. ltoreq. f 5/f. ltoreq.2.78 is satisfied.

The curvature radius R9 of the object side surface of the fifth lens L5 and the curvature radius R10 of the image side surface of the fifth lens L5 satisfy the following relations: -1.25 ≦ (R9+ R10)/(R9-R10) ≦ -0.10, and the shape of the fifth lens L5 is specified, and when the conditions are within the range, it is advantageous to correct the aberration of the off-axis view angle and the like as the ultra-thin wide angle is developed. Preferably, it satisfies-0.78 ≦ (R9+ R10)/(R9-R10) ≦ -0.13.

The fifth lens L5 has an on-axis thickness d9, and satisfies the following relationship: d9/TTL is more than or equal to 0.03 and less than or equal to 0.10, and ultra-thinning is facilitated. Preferably, 0.04. ltoreq. d 9/TTL. ltoreq.0.08 is satisfied.

The curvature radius R11 of the object side surface of the sixth lens L6 and the curvature radius R12 of the image side surface of the sixth lens L6 satisfy the following relations: -2.45 ≦ (R11+ R12)/(R11-R12) ≦ -0.02, and the shape of the sixth lens L6 is specified, and when the conditions are within the range, it is advantageous to correct the aberration of the off-axis view angle and the like as the ultra-thin wide angle is developed. Preferably, it satisfies-1.53 ≦ (R11+ R12)/(R11-R12). ltoreq.0.03.

The on-axis thickness of the sixth lens L6 is d11, and satisfies the following relation: d11/TTL is more than or equal to 0.03 and less than or equal to 0.15, and ultra-thinning is facilitated. Preferably, 0.04. ltoreq. d 11/TTL. ltoreq.0.12 is satisfied.

The focal length of the entire image pickup optical lens 10 is f, and the focal length of the seventh lens L7 is f7, and the following relations are satisfied: f7/f is more than or equal to 0.51 and less than or equal to 1.72, and the system has better imaging quality and lower sensitivity through reasonable distribution of the focal power. Preferably, 0.81. ltoreq. f 7/f. ltoreq.1.37 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 satisfy the following relations: -0.51 ≦ (R13+ R14)/(R13-R14) ≦ 0.30, and the shape of the seventh lens L7 is specified, and when the conditions are within the range, it is advantageous to correct the aberration of the off-axis view angle and the like as the ultra-thin wide angle is developed. Preferably, it satisfies-0.32. ltoreq. (R13+ R14)/(R13-R14). ltoreq.0.24.

The seventh lens L7 has an on-axis thickness d13, and satisfies the following relationship: d13/TTL is more than or equal to 0.08 and less than or equal to 0.36, and ultra-thinning is facilitated. Preferably, 0.13. ltoreq. d 13/TTL. ltoreq.0.29 is satisfied.

The focal length of the entire image pickup optical lens 10 is f, and the focal length of the eighth lens L8 is f8, and the following relations are satisfied: 1.40 ≦ f8/f ≦ -0.42, allowing better imaging quality and lower sensitivity of the system through reasonable distribution of optical power. Preferably, it satisfies-0.87. ltoreq. f 8/f. ltoreq-0.52.

The curvature radius R15 of the object side surface of the eighth lens L8 and the curvature radius R16 of the image side surface of the eighth lens L8 satisfy the following relations: 0.13 ≤ (R15+ R16)/(R15-R16) ≤ 0.72, and the shape of the eighth lens L8 is regulated, so that the aberration of off-axis picture angle can be corrected with the development of ultra-thin wide angle under the condition. Preferably, 0.20. ltoreq. (R15+ R16)/(R15-R16). ltoreq.0.58 is satisfied.

The eighth lens L8 has an on-axis thickness d15, and satisfies the following relationship: d15/TTL is more than or equal to 0.03 and less than or equal to 0.17, and ultra-thinning is facilitated. Preferably, 0.05. ltoreq. d 15/TTL. ltoreq.0.13 is satisfied.

In this embodiment, the combined focal length of the first lens L1 and the second lens L2 is defined as f12, and the following relation is satisfied: f12/f is not less than 0.22 and not more than 1.38, and within the range of the conditional 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, so as to keep the miniaturization of the image lens system. Preferably, 0.36. ltoreq. f 12/f. ltoreq.1.10.

In the present embodiment, the ratio between the total optical length TTL of the imaging optical lens 10 and the image height IH of the imaging optical lens 10 satisfies the following relationship: TTL/IH is less than or equal to 1.91, and ultra-thinning is facilitated.

In the present embodiment, the field angle FOV in the diagonal direction of the imaging optical lens 10 is equal to or larger than 68 °, 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: the total optical length (on-axis distance from the object side surface of the first lens L1 to the image plane) in units of 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: the on-axis distance from the image-side surface of the seventh lens L7 to the object-side surface of the optical filter GF;

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;

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.

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 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 ]

[ TABLE 4 ]

	Number of stagnation points	Location of stagnation 1	Location of stagnation 2
				P1R1	1	2.555
P1R2	0
				P2R1	0
P2R2	0
				P3R1	0
P3R2	1	1.815
				P4R1	0
P4R2	0
				P5R1	2	1.175	2.335
P5R2	0
				P6R1	0
P6R2	1	0.595
				P7R1	1	1.415
P7R2	0
				P8R1	0
P8R2	1	3.275

Fig. 2 and 3 are schematic diagrams showing axial aberrations and chromatic aberration of magnification of light having wavelengths of 650nm, 610nm, 555nm, 510nm, and 470nm, respectively, after passing through the imaging optical lens 10 according to the first embodiment. Fig. 4 is a schematic view showing curvature of field and distortion of light having a wavelength of 555nm after passing through the imaging optical lens 10 according to the first embodiment, where S is curvature of field in the sagittal direction and T is curvature of field in the tangential direction in fig. 4.

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 has an entrance pupil diameter of 4.048mm, a full field image height of 6.300mm, a diagonal field angle of 69.48 °, 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	2	1.805	2.605
P1R2	0
					P2R1	3	1.705	2.175	2.465
P2R2	0
					P3R1	1	0.755
P3R2	2	0.665	1.725
					P4R1	0
P4R2	0
					P5R1	2	1.465	1.905
P5R2	0
					P6R1	0
P6R2	1	0.385
					P7R1	1	1.045
P7R2	0
					P8R1	0
P8R2	1	1.565

[ TABLE 8 ]

Fig. 6 and 7 are schematic diagrams showing axial aberrations and chromatic aberration of magnification of light having wavelengths of 650nm, 610nm, 555nm, 510nm, and 470nm 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 555nm 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 has an entrance pupil diameter of 4.182mm, a full field height of 6.300mm, a diagonal field angle of 68.28 °, 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
				P1R1	1	1.375
P1R2	2	1.315	1.705
				P2R1	2	1.565	1.925
P2R2	0
				P3R1	0
P3R2	1	0.705
				P4R1	2	0.885	1.505
P4R2	0
				P5R1	2	1.135	2.005
P5R2	0
				P6R1	0
P6R2	0
				P7R1	1	1.095
P7R2	1	3.395
				P8R1	1	3.185
P8R2	1	1.235

[ TABLE 12 ]

	Number of stagnation points	Location of stagnation 1
			P1R1	0
P1R2	0
			P2R1	0
P2R2	0
			P3R1	0
P3R2	0
			P4R1	0
P4R2	0
			P5R1	1	1.815
P5R2	0
			P6R1	0
P6R2	0
			P7R1	1	2.065
P7R2	0
			P8R1	0
P8R2	1	3.255

Fig. 10 and 11 are schematic diagrams showing axial aberrations and chromatic aberration of magnification of light having wavelengths of 650nm, 610nm, 555nm, 510nm, and 470nm 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 555nm 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 has an entrance pupil diameter of 3.512mm, a full field height of 6.300mm, a diagonal field angle of 77.29 °, a wide angle, and a high profile, and has excellent optical characteristics with on-axis and off-axis chromatic aberration sufficiently corrected.

[ TABLE 13 ]

Parameter and condition formula	Example 1	Example 2	Example 3
				f1	26.54	30.00	45.06
f2/f	1.05	0.50	1.04
				n3	1.57	1.67	1.59
d1/d2	2.51	3.49	3.49
				(R1+R2)/(R1-R2)	-1.50	-3.47	-19.99
f	8.905	9.200	7.726
				f2	9.346	4.609	8.022
f3	-51.660	-7.280	-99.549
				f4	-14.542	-11.887	-12.118
f5	20.628	15.276	15.358
				f6	-26.067	-19.961	-34.672
f7	9.050	9.427	8.835
				f8	-5.550	-6.269	-5.400
f12	7.036	4.097	7.107
				Fno	2.20	2.20	2.20

Fno is the F-number of the diaphragm of the image pickup optical lens.

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 order 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; the first lens element with positive refractive power, the second lens element with positive refractive power, the third lens element with negative refractive power, the fourth lens element with negative 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;

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 refractive index of the third lens is n3, the on-axis thickness of the first lens is d1, the on-axis distance from the image side surface of the first lens to the object side surface of the second lens is d2, the curvature radius of the object side surface of the first lens is R1, the curvature radius of the image side surface of the first lens is R2, and the following relational expressions are satisfied:

f1≥0.00；

0.50≤f2/f≤1.05；

1.55≤n3≤1.70；

2.50≤d1/d2≤3.50；

-20.00≤(R1+R2)/(R1-R2)≤-1.50。

2. the imaging optical lens according to claim 1, wherein the sixth lens has a focal length f6 and satisfies the following relationship:

-4.50≤f6/f≤-2.00。

3. the image-capturing optical lens of claim 1, wherein the first lens has a focal length f1, an on-axis thickness d1, and an optical total length TTL that satisfies the following relationship:

1.49≤f1/f≤8.75；

0.01≤d1/TTL≤0.06。

4. the image-capturing optical lens unit according to claim 1, wherein 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, the on-axis thickness of the second lens element is d3, the total optical length of the image-capturing optical lens unit is TTL, and the following relationships are satisfied:

-0.24≤(R3+R4)/(R3-R4)≤0.58

0.03≤d3/TTL≤0.11。

5. the imaging optical lens of claim 1, wherein the third lens has a focal length of f3, a radius of curvature of an object-side surface of the third lens is R5, a radius of curvature of an image-side surface of the third lens is R6, an on-axis thickness of the third lens is d5, and the imaging optical lens has a total optical length of TTL and satisfies the following relationship:

-25.77≤f3/f≤-0.53；

-0.05≤(R5+R6)/(R5-R6)≤14.22；

0.02≤d5/TTL≤0.10。

6. the image-capturing optical lens unit according to claim 1, wherein the fourth lens element has a focal length f4, a radius of curvature of an object-side surface of the fourth lens element is R7, a radius of curvature of an image-side surface of the fourth lens element is R8, an on-axis thickness of the fourth lens element is d7, an optical total length of the image-capturing optical lens unit is TTL, and the following relationship is satisfied:

-3.27≤f4/f≤-0.86；

0.77≤(R7+R8)/(R7-R8)≤3.01；

0.01≤d7/TTL≤0.04。

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

0.83≤f5/f≤3.47；

-1.25≤(R9+R10)/(R9-R10)≤-0.10；

0.03≤d9/TTL≤0.10。

8. the image-capturing optical lens unit according to claim 1, wherein 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 image-capturing optical lens unit is TTL, and the following relationships are satisfied:

-2.45≤(R11+R12)/(R11-R12)≤-0.02；

0.03≤d11/TTL≤0.15。

9. the image-taking optical lens according to claim 1, wherein the seventh lens element has a focal length f7, 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, an optical total length of the image-taking optical lens is TTL, and the following relationship is satisfied:

0.51≤f7/f≤1.72；

-0.51≤(R13+R14)/(R13-R14)≤0.30；

0.08≤d13/TTL≤0.36。

10. the image-capturing optical lens unit 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, an on-axis thickness of the eighth lens element is d15, an optical total length of the image-capturing optical lens unit is TTL, and the following relationship is satisfied:

-1.40≤f8/f≤-0.42；

0.13≤(R15+R16)/(R15-R16)≤0.72；

0.03≤d15/TTL≤0.17。