CN110908090B

CN110908090B - Image pickup optical lens

Info

Publication number: CN110908090B
Application number: CN201911385159.9A
Authority: CN
Inventors: 许民益
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: CN110908090A

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 mm; f2/f is more than or equal to 1.60 and less than or equal to 4.50; n8 is more than or equal to 1.55 and less than or equal to 1.70; the ratio of (R13+ R14)/(R13-R14) is not less than-30.00 and not more than-3.00. The camera optical lens has good optical performance such as long focal length and ultrathin property.

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, five-piece, six-piece and eight-piece lens structures gradually appear in the design of the lens. There is a strong demand for long-focal-length and ultra-thin optical imaging lenses having excellent optical characteristics.

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 long focal length and an ultra-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 first mirror is f1, the refractive index of the eighth lens element is n8, the radius of curvature of the object-side surface of the seventh lens element is R13, and the radius of curvature of the image-side surface of the seventh lens element is R14, which satisfy the following relations: f1 is more than or equal to 0.00 mm; f2/f is more than or equal to 1.60 and less than or equal to 4.50; n8 is more than or equal to 1.55 and less than or equal to 1.70; the ratio of (R13+ R14)/(R13-R14) is not less than-30.00 and not more than-3.00.

Preferably, 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, and the following relation is satisfied: d1/d2 is more than or equal to 4.40 and less than or equal to 25.00.

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: f1/f is more than or equal to 0.35 and less than or equal to 1.13; -3.33 ≦ (R1+ R2)/(R1-R2) ≦ -0.74; d1/TTL is more than or equal to 0.03 and less than or equal to 0.17.

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: -4.45 ≤ (R3+ R4)/(R3-R4) ≤ 0.09; d3/TTL is more than or equal to 0.03 and less than or equal to 0.09.

Preferably, the focal length of the third lens is f3, the on-axis thickness of the third lens is d5, 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 image pickup optical lens is TTL, and the following relations are satisfied: -20.56. ltoreq. f 3/f. ltoreq.102.03; -93.50 ≤ (R5+ R6)/(R5-R6) 8.31; d5/TTL is more than or equal to 0.01 and less than or equal to 0.05.

Preferably, the focal length of the fourth lens element is f4, the on-axis thickness of the fourth lens element is d7, 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 total optical length of the image pickup optical lens is TTL, and the following relationships are satisfied: -3.49 ≤ f4/f ≤ 10.56; -67.79 (R7+ R8)/(R7-R8) is less than or equal to 12.28; d7/TTL is more than or equal to 0.01 and less than or equal to 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, 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: -3.58. ltoreq. f 5/f. ltoreq.3.76; -9.32 ≤ (R9+ R10)/(R9-R10) 3.31; d9/TTL is more than or equal to 0.01 and less than or equal to 0.05.

Preferably, the focal length of the sixth lens element is f6, the on-axis thickness of the sixth lens element is d11, 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, and the total optical length of the imaging optical lens system is TTL and satisfies the following relationships: f6/f is more than or equal to-1.18 and less than or equal to-0.35; (R11+ R12)/(R11-R12) is not more than 0.88 and not more than 3.08; d11/TTL is more than or equal to 0.01 and less than or equal to 0.04.

Preferably, the focal length of the seventh lens is f7, the on-axis thickness of the seventh lens is d13, the total optical length of the imaging optical lens is TTL, and the following relation is satisfied: f7/f is more than or equal to 1.08 and less than or equal to 18.40; d13/TTL is more than or equal to 0.01 and less than or equal to 0.23.

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, the total optical length of the imaging optical lens system is TTL, and the following relationships are satisfied: f8/f is more than or equal to 0.74 and less than or equal to 2.69; less than or equal to 9.31 (R15+ R16)/(R15-R16) less than or equal to-1.80; d15/TTL is more than or equal to 0.12 and less than or equal to 0.43.

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 long focal length and ultra-thin, 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 a CCD, a CMOS and the like for high pixel.

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 image pickup optical lens 10 according to a first embodiment of the present invention, and the image pickup optical lens 10 includes seven 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.

The focal length of the first lens L1 is f1, f1 is larger than or equal to 0.00mm, 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. Preferably, f1 ≧ 4.34mm is satisfied.

The focal length of the entire image pickup optical lens 10 is f, and the focal length of the second lens L2 is f2, and the following relations are satisfied: f2/f is more than or equal to 1.60 and less than or equal to 4.50, the ratio of the focal length of the second 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. Preferably, 1.63. ltoreq. f 2/f. ltoreq.4.49 is satisfied.

The refractive index of the eighth lens is n8, and the following relational expression is satisfied: 1.55 is less than or equal to n8 is less than or equal to 1.70, the refractive index of the eighth lens is specified, and the optical system performance is improved within the conditional expression range. Preferably, 1.56. ltoreq. n 8. ltoreq.1.69 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: 30.00 ≦ (R13+ R14)/(R13-R14) ≦ -3.00, and defines the shape of the seventh lens L7, and within the range defined by the conditional expression, the degree of deflection of the light passing through the lens can be alleviated, and the aberration can be effectively reduced. Preferably, it satisfies-29.73 ≦ (R13+ R14)/(R13-R14) ≦ -3.50.

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 requirement of low TTL.

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, d1/d2 is more than or equal to 4.40 and less than or equal to 25.00, the ratio of the thickness of the first lens to the air space of the first lens and the air space of the second lens is specified, the total optical length is favorably compressed within the conditional expression range, and the ultrathin effect is realized. Preferably, 4.41. ltoreq. d1/d 2. ltoreq.24.59 is satisfied.

The focal length of the first lens L1 is f1, f1/f is more than or equal to 0.35 and less than or equal to 1.13, 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, 0.56. ltoreq. f 1/f. ltoreq.0.90 is satisfied.

The curvature radius R1 of the object side surface of the first lens L1 and the curvature radius R2 of the image side surface of the first lens L1 satisfy the following relations: 3.33 ≦ (R1+ R2)/(R1-R2) ≦ -0.74, and the shape of the first lens is appropriately controlled so that the first lens can effectively correct the system spherical aberration. Preferably, it satisfies-2.08 ≦ (R1+ R2)/(R1-R2) ≦ -0.92.

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 0.03 and less than or equal to 0.17, and ultra-thinning is facilitated. Preferably, 0.05. ltoreq. d 1/TTL. ltoreq.0.14 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, -4.45 (R3+ R4)/(R3-R4) is less than or equal to-0.09, 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-2.78 ≦ (R3+ R4)/(R3-R4) ≦ -0.12.

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 0.09, and ultra-thinning is facilitated. Preferably, 0.04. ltoreq. d 3/TTL. ltoreq.0.07 is satisfied.

The focal length of the entire image pickup optical lens 10 is f, the focal length of the third lens L3 is f3, and the following relationships are satisfied: 20.56 ≦ f3/f ≦ 102.03, which allows better imaging quality and lower sensitivity of the system by a reasonable distribution of the powers. F3/f is more than or equal to-12.85 and less than or equal to 81.62.

The curvature radius R5 of the object side surface of the third lens L3 and the curvature radius R6 of the image side surface of the third lens L3 satisfy the following relations: 93.50 ≦ (R5+ R6)/(R5-R6) ≦ 8.31, 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, and effectively reduce aberration. Preferably, it satisfies-58.44 ≦ (R5+ R6)/(R5-R6). ltoreq.6.65.

The on-axis thickness of the third lens L3 is d5, and satisfies the following relation: d5/TTL is more than or equal to 0.01 and less than or equal to 0.05, and ultra-thinning is facilitated. Preferably, 0.02. ltoreq. d 5/TTL. ltoreq.0.04 is satisfied.

The focal length of the whole shooting optical lens 10 is defined as f, the focal length of the fourth lens L4 is defined as f4, -3.49 ≤ f4/f ≤ 10.56, and the system has better imaging quality and lower sensitivity through reasonable distribution of focal power. Preferably, it satisfies-2.18. ltoreq. f 4/f. ltoreq.8.45.

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, -67.79 (R7+ R8)/(R7-R8) is 12.28 or less, and the shape of the fourth lens L4 is defined, so that when the curvature radius is within the range, problems such as off-axis aberration and the like are favorably corrected with the development of ultra-thin and wide-angle angles. Preferably, it satisfies-42.37 ≦ (R7+ R8)/(R7-R8). ltoreq.9.82.

The on-axis thickness of the fourth lens L4 is d7, and satisfies the following relation: d7/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 7/TTL. ltoreq.0.05 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: 3.58 ≦ f5/f ≦ 3.76, and the definition of the fifth lens L5 can effectively make the light angle of the camera lens gentle and reduce the tolerance sensitivity. Preferably, it satisfies-2.24. ltoreq. f 5/f. ltoreq.3.01.

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: 9.32 ≦ (R9+ R10)/(R9-R10) ≦ 3.31, 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-5.82 ≦ (R9+ R10)/(R9-R10). ltoreq.2.65.

The fifth lens L5 has an on-axis thickness d9, and satisfies the following relationship: d9/TTL is more than or equal to 0.01 and less than or equal to 0.05, and ultra-thinning is facilitated. Preferably, 0.01. ltoreq. d 9/TTL. ltoreq.0.04 is satisfied.

The focal length of the entire image pickup optical lens 10 is f, and the focal length of the sixth lens L6 is f6, and the following relationships are satisfied: 1.18 ≦ f6/f ≦ -0.35, allowing better imaging quality and lower sensitivity of the system through reasonable distribution of optical power. Preferably, it satisfies-0.73. ltoreq. f 6/f. ltoreq-0.44.

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: the (R11+ R12)/(R11-R12) is not more than 0.88 and not more than 3.08, and the shape of the sixth lens L6 is defined, and when the shape is within the condition range, the problem of aberration of off-axis picture angle is favorably corrected along with the development of ultra-thin wide-angle. Preferably, 1.40. ltoreq. (R11+ R12)/(R11-R12). ltoreq.2.46 is satisfied.

The on-axis thickness of the sixth lens L6 is d11, and satisfies the following relation: d11/TTL is more than or equal to 0.01 and less than or equal to 0.04, which is beneficial to realizing ultra-thinning. Preferably, 0.01. ltoreq. d 11/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 seventh lens L7 is f7, and the following relations are satisfied: 1.08 ≦ f7/f ≦ 18.40, and the system has better imaging quality and lower sensitivity through reasonable distribution of the focal power. Preferably, 1.72. ltoreq. f 7/f. ltoreq.14.72 is satisfied.

The seventh lens L7 has an on-axis thickness d13, and satisfies the following relationship: d13/TTL is more than or equal to 0.01 and less than or equal to 0.23, and ultra-thinning is facilitated. Preferably, 0.01. ltoreq. d 13/TTL. ltoreq.0.18 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: 0.74 ≦ f8/f ≦ 2.69, which makes the system have better imaging quality and lower sensitivity through reasonable distribution of the focal power. Preferably, 1.18. ltoreq. f 8/f. ltoreq.2.15 is satisfied.

The curvature radius R15 of the object side surface of the eighth lens L8 and the curvature radius R17 of the image side surface of the eighth lens L8 satisfy the following relations: 9.31 ≦ (R15+ R16)/(R15-R16) ≦ -1.80, and the shape of the eighth lens L8 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-5.82 ≦ (R15+ R16)/(R15-R16) ≦ -2.24.

The eighth lens L8 has an on-axis thickness d15, and satisfies the following relationship: d15/TTL is more than or equal to 0.12 and less than or equal to 0.43, and ultra-thinning is facilitated. Preferably, 0.19. ltoreq. d 15/TTL. ltoreq.0.35 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 more than or equal to 0.27 and less than or equal to 0.93, 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, 0.43. ltoreq. f 12/f. ltoreq.0.75.

In the present embodiment, the ratio between the effective focal length EFL of the image pickup optical lens 10 and the total optical length TTL of the image pickup optical lens 10 satisfies the following relational expression: EFL/TTL is more than or equal to 0.84, and ultra-thinning is facilitated.

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: 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 15: on-axis thickness of the optical filter GF;

d 16: 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.

[ 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 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	Position of reverse curve 4
						P1R1	0
P1R2	0
						P2R1	1	1.925
P2R2	4	0.665	0.955	1.615	1.975
						P3R1	2	1.445	1.815
P3R2	3	0.305	0.515	1.835
						P4R1	2	1.775	1.945
P4R2	1	1.635
						P5R1	0
P5R2	4	1.055	1.075	1.325	1.715
						P6R1	1	1.305
P6R2	2	1.635	1.705
						P7R1	2	1.015	1.705
P7R2	1	1.185
						P8R1	0
P8R2	2	1.535	1.675

[ TABLE 4 ]

	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	0
P5R2	0
			P6R1	1	1.605
P6R2	0
			P7R1	1	1.395
P7R2	1	1.685
			P8R1	0
P8R2	0

Fig. 2 and 3 are schematic diagrams showing axial aberrations and chromatic aberration of magnification of light having wavelengths of 486nm, 588nm, and 656nm 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 588nm 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 4.714mm, a full field image height of 2.50mm, a diagonal field angle of 22.74 °, a long focal length, 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	Position of reverse curve 4	Position of reverse curve 5	Position 6 of reverse curve
								P1R1
	0
								P1R2	1	2.155
P2R1	1	1.955
								P2R2	4	0.565	0.975	1.585	1.965
P3R1	2	1.555	1.825
								P3R2	1	1.865
P4R1	1	1.745
								P4R2	1	1.605
P5R1	0
								P5R2	6	1.075	1.085	1.385	1.535	1.635	1.705
P6R1	2	1.445	1.755
								P6R2	0
P7R1	1	1.085
								P7R2	1	1.175
P8R1	0
								P8R2	0

[ TABLE 8 ]

Fig. 6 and 7 are schematic diagrams showing axial aberrations and chromatic aberration of magnification of light having wavelengths of 486nm, 588nm and 656nm 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 588nm 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 4.610mm, a full field image height of 2.50mm, a diagonal field angle of 23.39 °, 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	0
P1R2	2	0.875	1.615
				P2R1	0
P2R2	1	1.115
				P3R1	2	0.415	1.495
P3R2	1	1.935
				P4R1	1	1.305
P4R2	1	1.335
				P5R1	0
P5R2	2	1.495	1.655
				P6R1	2	1.795	1.895
P6R2	2	1.805	1.845
				P7R1	1	1.725
P7R2	1	2.055
				P8R1	0
P8R2	0

[ TABLE 12 ]

	Number of stagnation points	Location of stagnation 1	Location of stagnation 2
				P1R1	0
P1R2	2	1.235	1.885
				P2R1	0
P2R2	1	1.885
				P3R1	2	0.595	1.855
P3R2	0
				P4R1	1	1.995
P4R2	1	2.015
				P5R1	0
P5R2	0
				P6R1	0
P6R2	0
				P7R1	0
P7R2	0
				P8R1	0
P8R2	0

Fig. 10 and 11 are schematic diagrams showing axial aberrations and chromatic aberration of magnification of light having wavelengths of 486nm, 588nm, and 656nm 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 588nm 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 4.615mm, a full field image height of 2.50mm, a diagonal field angle of 23.52 °, a wide angle, and a thin 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
				f	12.293	11.986	12.000
f1	8.67	8.69	9.04
				f2	54.966	37.342	19.801
f3	836.167	-123.224	-51.456
				f4	-18.006	-20.891	84.470
f5	19.644	30.035	-21.506
				f6	-6.522	-7.044	-6.676
f7	150.810	92.365	25.868
				f8	18.113	18.972	21.491
f12	7.635	7.255	6.408
				Fno	2.61	2.60	2.60
f2/f	4.47	3.12	1.65
				n8	1.67	1.62	1.57
(R13+R14)/(R13-R14)	-29.45	-15.99	-4.00
				d1/d2	4.43	11.49	24.18

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 sixth lens element with negative refractive power, the seventh lens element with positive refractive power, and the eighth lens element with positive 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 focal length of the fifth lens is f5, the refractive index of the eighth lens is n8, the radius of curvature of the object-side surface of the seventh lens is R13, and the radius of curvature of the image-side surface of the seventh lens is R14, which satisfy the following relations:

-3.58≤f5/f≤3.76；

f1≥4.34mm；

1.60≤f2/f≤4.50；

1.55≤n8≤1.70；

-30.00≤(R13+R14)/(R13-R14)≤-3.00。

2. the imaging optical lens according to claim 1, wherein an on-axis thickness of the first lens is d1, an on-axis distance from an image-side surface of the first lens to an object-side surface of the second lens is d2, and the following relationship is satisfied:

4.40≤d1/d2≤25.00。

3. the image-capturing optical lens unit according to claim 1, wherein the radius of curvature of the object-side surface of the first lens element is R1, the radius of curvature of the image-side surface of the first lens element is R2, the on-axis thickness of the first lens element is d1, the total optical length of the image-capturing optical lens unit is TTL, and the following relationships are satisfied:

0.35≤f1/f≤1.13；

-3.33≤(R1+R2)/(R1-R2)≤-0.74；

0.03≤d1/TTL≤0.17。

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:

-4.45≤(R3+R4)/(R3-R4)≤-0.09；

0.03≤d3/TTL≤0.09。

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

-20.56≤f3/f≤102.03；

-93.50≤(R5+R6)/(R5-R6)≤8.31；

0.01≤d5/TTL≤0.05。

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

-3.49≤f4/f≤10.56；

-67.79≤(R7+R8)/(R7-R8)≤12.28；

0.01≤d7/TTL≤0.06。

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

-9.32≤(R9+R10)/(R9-R10)≤3.31；

0.01≤d9/TTL≤0.05。

8. the image-taking optical lens according to claim 1, wherein the sixth lens element has a focal length f6, an on-axis thickness d11, 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, and an optical total length TTL, and satisfies the following relationship:

-1.18≤f6/f≤-0.35；

0.88≤(R11+R12)/(R11-R12)≤3.08；

0.01≤d11/TTL≤0.04。

9. the image-capturing optical lens of claim 1, wherein the seventh lens has a focal length f7, an on-axis thickness d13, a total optical length TTL, and the following relationship is satisfied:

1.08≤f7/f≤18.40；

0.01≤d13/TTL≤0.23。

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:

0.74≤f8/f≤2.69；

-9.31≤(R15+R16)/(R15-R16)≤-1.80；

0.12≤d15/TTL≤0.43。