CN114415352A - Optical system for image pickup - Google Patents

Abstract

The invention discloses an optical system for shooting, which comprises eight lenses, wherein the eight lenses are 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 from an object side to an image side in sequence. The eight lenses respectively have object side surfaces facing the object side direction and image side surfaces facing the image side direction. The first lens element has positive refractive power. The second lens element has a convex object-side surface at a paraxial region. The fifth lens element with positive refractive power. The seventh lens element has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region. The image-side surface of the eighth lens element is concave at a paraxial region. At least one surface of at least one lens in the image pickup optical system has at least one critical point at the off-axis position. When specific conditions are satisfied, the optical system for image pickup can satisfy both the demands for miniaturization and high image quality.

Description

Optical system for imaging

This application is a divisional application. The application date of the original application is: November 27, 2019; the application number is: 201911183015.5; the name of the invention is: optical system for imaging, imaging device and electronic device.

technical field

The invention relates to an optical system for imaging, in particular to an optical system for imaging that can meet the requirements of miniaturization and high imaging quality at the same time.

Background technique

With the improvement of semiconductor technology, the performance of electronic photosensitive elements has been improved, and the pixel size can be smaller. Therefore, optical lenses with high imaging quality have become an indispensable part.

With the rapid development of science and technology, the application range of electronic devices equipped with optical lenses is wider, and the requirements for optical lenses are also more diverse. Since it is difficult to achieve a balance among the requirements of imaging quality, sensitivity, aperture size, volume or viewing angle, etc. of the optical lens in the past, the present invention provides an optical lens to meet the requirements.

SUMMARY OF THE INVENTION

The present invention provides an imaging optical system. Among them, the imaging optical system includes eight lenses. When certain conditions are met, the imaging optical system provided by the present invention can meet the requirements of miniaturization and high imaging quality at the same time.

The invention provides an optical system for imaging, comprising eight lenses. The eight lenses are 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 in sequence from the object side to the image side. The eight lenses each have an object-side surface toward the object-side direction and an image-side surface toward the image-side direction. The first lens has positive refractive power. The object-side surface of the second lens is convex at the near optical axis. The fifth lens has positive refractive power. The object-side surface of the seventh lens is convex at the near optical axis, and the image-side surface of the seventh lens is concave at the near optical axis. The image-side surface of the eighth lens is concave at the near optical axis. At least one surface of at least one lens in the imaging optical system has at least one critical point off-axis. The Abbe number of the second lens is V2, the focal length of the imaging optical system is f, the focal length of the first lens is f1, the focal length of the fifth lens is f5, the focal length of the seventh lens is f7, and the focal length of the eighth lens is f8 , the radius of curvature of the object-side surface of the second lens is R3, the radius of curvature of the object-side surface of the sixth lens is R11, the radius of curvature of the image-side surface of the sixth lens is R12, the thickness of the second lens on the optical axis is CT2, and the The thickness of the three lenses on the optical axis is CT3, which satisfies the following conditions:

10.0<V2<50.0;

0<f5/f1<9.5;

-7.5<f8/f7<-0.55;

0<R3/f<2.0;

2.5<f/|R11|+f/|R12|<7.5; and

0.10<CT3/CT2<1.5.

The present invention further provides an optical system for imaging, comprising eight lenses. The eight lenses are 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 in sequence from the object side to the image side. The eight lenses each have an object-side surface toward the object-side direction and an image-side surface toward the image-side direction. The first lens has positive refractive power. The object-side surface of the second lens is convex at the near optical axis. The fifth lens has positive refractive power. The object-side surface of the seventh lens is convex at the near optical axis, and the image-side surface of the seventh lens is concave at the near optical axis. The image-side surface of the eighth lens is concave at the near optical axis. At least one surface of at least one lens in the imaging optical system has at least one critical point off-axis. The Abbe number of the second lens is V2, the focal length of the imaging optical system is f, the focal length of the first lens is f1, the focal length of the fifth lens is f5, the focal length of the seventh lens is f7, and the focal length of the eighth lens is f8 , the radius of curvature of the object-side surface of the second lens is R3, the radius of curvature of the object-side surface of the fifth lens is R9, the radius of curvature of the image-side surface of the fifth lens is R10, the radius of curvature of the object-side surface of the sixth lens is R11, and the The radius of curvature of the six-lens image-side surface is R12, which satisfies the following conditions:

10.0<V2<50.0;

0<f5/f1<9.5;

-7.5<f8/f7<-0.55;

0<R3/f<2.0;

2.5<f/|R11|+f/|R12|<7.5; and

-1.5<(R9+R10)/(R9-R10)<1.5.

The present invention further provides an optical system for imaging, comprising eight lenses. The eight lenses are 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 in sequence from the object side to the image side. The eight lenses each have an object-side surface toward the object-side direction and an image-side surface toward the image-side direction. The first lens has positive refractive power. The object-side surface of the second lens is convex at the near optical axis. The fifth lens has positive refractive power. The object-side surface of the seventh lens is convex at the near optical axis, and the image-side surface of the seventh lens is concave at the near optical axis. The image-side surface of the eighth lens is concave at the near optical axis. At least one surface of at least one lens in the imaging optical system has at least one critical point off-axis. The Abbe number of the second lens is V2, the focal length of the imaging optical system is f, the focal length of the first lens is f1, the focal length of the third lens is f3, the focal length of the fifth lens is f5, and the focal length of the seventh lens is f7 , the focal length of the eighth lens is f8, the radius of curvature of the object-side surface of the second lens is R3, the radius of curvature of the object-side surface of the sixth lens is R11, and the radius of curvature of the image-side surface of the sixth lens is R12, which satisfy the following conditions:

10.0<V2<50.0;

0<f5/f1<9.5;

-7.5<f8/f7<-0.55;

0<R3/f<2.0;

2.5<f/|R11|+f/|R12|<7.5; and

-0.40<f/f3<0.40.

When V2 satisfies the above conditions, the material of the second lens can be adjusted to help correct aberrations such as chromatic aberration.

When f5/f1 satisfies the above conditions, the refractive power distribution of the imaging optical system can be adjusted to compress the volume and adjust the volume distribution.

When f8/f7 satisfies the above conditions, the refractive powers of the seventh lens and the eighth lens can be matched with each other to correct aberrations such as spherical aberration.

When R3/f satisfies the above conditions, the surface shape and refractive power of the second lens can be adjusted to correct aberrations.

When f/|R11|+f/|R12| satisfies the above conditions, the surface shape and refractive power of the sixth lens can be adjusted, which is helpful to cooperate with the fifth lens to correct aberrations.

When CT3/CT2 satisfies the above conditions, the second lens and the third lens can cooperate with each other, which helps to compress the volume at the object side of the imaging optical system.

When (R9+R10)/(R9-R10) satisfies the above conditions, the surface shape of the fifth lens can be adjusted to control the direction of light travel, which helps to achieve a balance between viewing angle, volume and imaging surface size.

When f/f3 meets the above conditions, the refractive power of the lens can be adjusted, which helps to correct aberrations, compress the volume and adjust the viewing angle.

The above description of the content of the present invention and the description of the following embodiments are used to demonstrate and explain the spirit and principle of the present invention, and provide further explanation of the protection scope of the patent application claims of the present invention.

Description of drawings

FIG. 1 is a schematic diagram of an imaging device according to a first embodiment of the present invention.

FIG. 2 is a graph of spherical aberration, astigmatism, and distortion of the first embodiment from left to right.

FIG. 3 is a schematic diagram of an imaging device according to a second embodiment of the present invention.

FIG. 4 is a graph of spherical aberration, astigmatism, and distortion of the second embodiment from left to right.

FIG. 5 is a schematic diagram of an imaging device according to a third embodiment of the present invention.

FIG. 6 is a graph of spherical aberration, astigmatism, and distortion of the third embodiment from left to right.

FIG. 7 is a schematic diagram of an imaging device according to a fourth embodiment of the present invention.

FIG. 8 is a graph of spherical aberration, astigmatism, and distortion of the fourth embodiment from left to right.

FIG. 9 is a schematic diagram of an imaging device according to a fifth embodiment of the present invention.

FIG. 10 is a graph of spherical aberration, astigmatism and distortion of the fifth embodiment from left to right.

FIG. 11 is a schematic diagram of an imaging device according to a sixth embodiment of the present invention.

FIG. 12 is a graph showing spherical aberration, astigmatism and distortion of the sixth embodiment in order from left to right.

FIG. 13 is a schematic diagram of an imaging device according to a seventh embodiment of the present invention.

FIG. 14 is a graph of spherical aberration, astigmatism, and distortion of the seventh embodiment from left to right.

FIG. 15 is a schematic diagram of an imaging device according to an eighth embodiment of the present invention.

FIG. 16 is a graph of spherical aberration, astigmatism, and distortion of the eighth embodiment from left to right.

FIG. 17 is a schematic diagram of an imaging device according to a ninth embodiment of the present invention.

FIG. 18 is a graph showing spherical aberration, astigmatism and distortion of the ninth embodiment from left to right.

FIG. 19 is a schematic diagram of an imaging device according to a tenth embodiment of the present invention.

FIG. 20 is a graph of spherical aberration, astigmatism and distortion of the tenth embodiment from left to right.

FIG. 21 is a perspective view of an imaging device according to an eleventh embodiment of the present invention.

22 is a perspective view of one side of an electronic device according to a twelfth embodiment of the present invention.

FIG. 23 is a perspective view of another side of the electronic device of FIG. 22 .

FIG. 24 is a system block diagram of the electronic device of FIG. 22 .

FIG. 25 is a schematic diagram illustrating parameters Y11 , Y82 , Yc71 , Yc72 , Yc82 and the inflection point and critical point of each lens according to the first embodiment of the present invention.

Among them, reference numerals:

10, 10a, 10b: imaging device

11: Imaging lens

12: Drive unit

13: Electronic photosensitive element

14: Image stabilization module

20: Electronics

21: Flash Module

22: Focus Assist Module

23: Image signal processor

24: User Interface

25: Image software processor

26: Subject

P: Inflection point

C: critical point

100, 200, 300, 400, 500, 600, 700, 800, 900, 1000: Aperture

101, 201, 202, 301, 401, 402, 501, 502, 601, 602, 701, 801, 901, 902, 1001: Aperture

110, 210, 310, 410, 510, 610, 710, 810, 910, 1010: first lens

111, 211, 311, 411, 511, 611, 711, 811, 911, 1011: Object side surface

112, 212, 312, 412, 512, 612, 712, 812, 912, 1012: Image side surface

120, 220, 320, 420, 520, 620, 720, 820, 920, 1020: Second lens

121, 221, 321, 421, 521, 621, 721, 821, 921, 1021: Object side surface

122, 222, 322, 422, 522, 622, 722, 822, 922, 1022: Image side surface

130, 230, 330, 430, 530, 630, 730, 830, 930, 1030: Third lens

131, 231, 331, 431, 531, 631, 731, 831, 931, 1031: Object side surface

132, 232, 332, 432, 532, 632, 732, 832, 932, 1032: Image side surface

140, 240, 340, 440, 540, 640, 740, 840, 940, 1040: Fourth lens

141, 241, 341, 441, 541, 641, 741, 841, 941, 1041: Object side surface

142, 242, 342, 442, 542, 642, 742, 842, 942, 1042: Image side surface

150, 250, 350, 450, 550, 650, 750, 850, 950, 1050: Fifth lens

151, 251, 351, 451, 551, 651, 751, 851, 951, 1051: Object side surface

152, 252, 352, 452, 552, 652, 752, 852, 952, 1052: Image side surface

160, 260, 360, 460, 560, 660, 760, 860, 960, 1060: sixth lens

161, 261, 361, 461, 561, 661, 761, 861, 961, 1061: Object side surface

162, 262, 362, 462, 562, 662, 762, 862, 962, 1062: Image side surface

170, 270, 370, 470, 570, 670, 770, 870, 970, 1070: seventh lens

171, 271, 371, 471, 571, 671, 771, 871, 971, 1071: Object side surface

172, 272, 372, 472, 572, 672, 772, 872, 972, 1072: Image side surface

180, 280, 380, 480, 580, 680, 780, 880, 980, 1080: Eighth lens

181, 281, 381, 481, 581, 681, 781, 881, 981, 1081: Object side surface

182, 282, 382, 482, 582, 682, 782, 882, 982, 1082: Image side surface

190, 290, 390, 490, 590, 690, 790, 890, 990, 1090: Filter elements

195, 295, 395, 495, 595, 695, 795, 895, 995, 1095: Imaging plane

199, 299, 399, 499, 599, 699, 799, 899, 999, 1099: Electronic photosensitive elements

Y11: Maximum effective radius of the object-side surface of the first lens

Y82: The maximum effective radius of the image side surface of the eighth lens

Yc71: The vertical distance between the critical point on the object-side surface of the seventh lens and the optical axis

Yc72: The vertical distance between the critical point of the image-side surface of the seventh lens and the optical axis

Yc82: The vertical distance between the critical point of the image-side surface of the eighth lens and the optical axis

Detailed ways

The detailed features and advantages of the present invention are described in detail in the following embodiments, and the content is sufficient to enable any person skilled in the art to understand the technical content of the present invention and implement it accordingly, and according to the content disclosed in this specification, the protection scope of claims and With the accompanying drawings, any person skilled in the art can easily understand the related objects and advantages of the present invention. The following examples further illustrate the concept of the present invention in further detail, but are not intended to limit the scope of the present invention in any way.

The imaging optical system includes eight lenses, and the eight lenses are the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the Eighth lens. The eight lenses respectively have an object-side surface facing the object-side direction and an image-side surface facing the image-side direction.

The first lens has a positive refractive power; thereby, it contributes to compressing the volume of the imaging optical system. The object-side surface of the first lens can be a convex surface at the near optical axis; thereby, the light rays of each field of view can enter the imaging optical system uniformly, which helps to improve the relative illuminance around the imaging surface.

The object-side surface of the second lens can be convex at the near optical axis; thereby, it can cooperate with the first lens to correct aberrations. The image-side surface of the second lens can be concave at the near optical axis; thereby, it is helpful to correct aberrations such as astigmatism.

The fifth lens has a positive refractive power; thereby, it helps to compress the volume of the imaging optical system.

The seventh lens may have a positive refractive power; thereby, the distribution of the positive refractive power may be dispersed, helping to reduce the sensitivity of each lens when compressing the volume. The object-side surface of the seventh lens is convex at the near optical axis; thereby, the refractive power of the seventh lens can be adjusted, and the off-axis aberration can be corrected.

The eighth lens may have a negative refractive power; thereby, the distribution of the refractive power at the image side end of the imaging optical system can be balanced, so as to reduce aberrations such as spherical aberration. The image-side surface of the eighth lens is concave at the near optical axis; thereby, the length of the back focal length can be adjusted, and the off-axis aberration of image bending can be corrected.

In the imaging optical system disclosed in the present invention, at least one of the object-side surface and the image-side surface of at least one lens has at least one critical point off-axis; thereby, the degree of change of the lens surface can be improved, which is helpful for Correct off-axis aberration and improve the peripheral illumination of the imaging surface. Wherein, in the imaging optical system, at least two lenses may each have at least one critical point off-axis on at least one of the object-side surface and the image-side surface. Wherein, in the imaging optical system, at least three lenses may each have at least one critical point off-axis on at least one of the object-side surface and the image-side surface. Wherein, at least one of the object-side surface of the sixth lens and the image-side surface of the sixth lens may have at least one critical point off-axis; thereby, it is helpful to adjust the image-side volume distribution of the imaging optical system. Wherein, the object-side surface of the seventh lens may have at least one critical point off-axis; thereby, the incident angle of light on the seventh lens can be adjusted, which helps to reduce the generation of stray light. Wherein, the image-side surface of the seventh lens may have at least one critical point off-axis; thereby, it can cooperate with the eighth lens to further correct off-axis aberrations. Among them, the vertical distance between the critical point on the object-side surface of the seventh lens and the optical axis is Yc71, the vertical distance between the critical point on the image-side surface of the seventh lens and the optical axis is Yc72, and the object-side surface of the seventh lens is off-axis. At least one critical point at and at least one critical point of the image-side surface of the seventh lens at off-axis can satisfy the following conditions: 0.80<Yc72/Yc71<1.5; thereby, the surface shape of the seventh lens can be adjusted to further correct the off-axis aberrations. Wherein, at least one critical point on the object side surface of the seventh lens off-axis and at least one critical point on the image side surface of the seventh lens off-axis can also satisfy the following conditions: 0.90<Yc72/Yc71<1.4. Wherein, the image-side surface of the eighth lens may have at least one critical point off-axis; thereby, off-axis aberration can be corrected, and the incident angle of light on the imaging surface can be adjusted, so as to improve the illuminance and electronic sensitivity of the imaging surface Response efficiency of components. The vertical distance between the critical point of the image-side surface of the eighth lens and the optical axis is Yc82, the maximum effective radius of the image-side surface of the eighth lens is Y82, and at least one critical point of the image-side surface of the eighth lens is off-axis The following conditions can be satisfied: 0.20<Yc82/Y82<0.60; thereby, the surface shape of the eighth lens can be adjusted to further improve the imaging quality. Wherein, at least one critical point of the image-side surface of the eighth lens that is off-axis may also satisfy the following condition: 0.30<Yc82/Y82<0.50. Please refer to FIG. 25, which shows the critical point C and the parameters Yc71, Yc72, Schematic representation of Yc82 and Y82.

In the imaging optical system disclosed in the present invention, each of at least three lenses may have at least one inflection point on at least one of the object-side surface and the image-side surface; thereby, the degree of lens surface variation can be improved , which helps correct aberrations and compress the volume. Wherein, in the imaging optical system, at least four lenses may each have at least one inflection point on at least one of the object-side surface and the image-side surface. Wherein, in the imaging optical system, at least five lenses may each have at least one inflection point on at least one of the object-side surface and the image-side surface. Wherein, all the lenses in the imaging optical system may each have at least one inflection point on the object-side surface and the image-side surface; thereby, the degree of surface variation of the lens can be further improved to correct aberrations and compress the volume. Please refer to FIG. 25 , which is a schematic diagram of the inflection point P of each lens according to the first embodiment of the present invention.

The distance between the seventh lens and the eighth lens on the optical axis may be the largest one among the distances between the two adjacent lenses on the optical axis in the imaging optical system. In this way, the lens distribution can be adjusted, which helps to increase the imaging surface area and correct off-axis aberrations. In the present invention, the distance between two adjacent lenses on the optical axis refers to the distance between two adjacent mirror surfaces of two adjacent lenses on the optical axis.

The Abbe number of the second lens is V2, which satisfies the following condition: 10.0<V2<50.0. Thereby, the material of the second lens can be adjusted, which helps to correct aberrations such as chromatic aberration. Among them, the following conditions can also be satisfied: 11.0<V2<40.0. Among them, the following conditions can also be satisfied: 12.0<V2<30.0. Among them, the following conditions can also be satisfied: 13.0<V2<25.0.

The focal length of the first lens is f1, and the focal length of the fifth lens is f5, which satisfy the following conditions: 0<f5/f1; or f5/f1<9.5. Thereby, the refractive power distribution of the imaging optical system can be adjusted to compress the volume and adjust the volume distribution. Among them, the following conditions can also be satisfied: 0.10<f5/f1. Among them, the following conditions can also be satisfied: 0.30<f5/f1. Among them, the following conditions can also be satisfied: 0.50<f5/f1. Among them, the following conditions can also be satisfied: f5/f1<5.0. Among them, the following conditions can also be satisfied: f5/f1<3.0. Among them, the following conditions can also be satisfied: f5/f1<2.0. Among them, the following conditions can also be satisfied: 0<f5/f1<9.5. Among them, the following conditions can also be satisfied: 0<f5/f1<3.0. Among them, the following conditions can also be satisfied: 0.10<f5/f1<5.0. Among them, the following conditions can also be satisfied: 0.30<f5/f1<2.0.

The thickness of the fifth lens on the optical axis is CT5, and the thickness of the seventh lens on the optical axis is CT7, which can satisfy the following conditions: 0.10<CT7/CT5<1.3. Thereby, the lens distribution on the image side of the imaging optical system can be adjusted, which contributes to compressing the volume on the image side. Among them, the following conditions can also be satisfied: 0.20<CT7/CT5<1.0. Among them, the following conditions can also be satisfied: 0.40<CT7/CT5<0.70.

The thickness of the second lens on the optical axis is CT2, and the thickness of the third lens on the optical axis is CT3, which can satisfy the following conditions: 0.10<CT3/CT2<1.5. In this way, the second lens and the third lens can cooperate with each other, which contributes to compressing the volume at the object side of the imaging optical system. Among them, the following conditions can also be satisfied: 0.60<CT3/CT2<1.5. Among them, the following conditions can also be satisfied: 0.80<CT3/CT2<1.5.

The focal length of the seventh lens is f7, and the focal length of the eighth lens is f8, which can satisfy the following condition: -7.5<f8/f7<-0.55. In this way, the refractive powers of the seventh lens and the eighth lens can be matched with each other to correct aberrations such as spherical aberration. Among them, the following conditions can also be satisfied: -4.0<f8/f7<-0.60. Among them, the following conditions can also be satisfied: -1.5<f8/f7<-0.65.

The curvature radius of the object-side surface of the second lens is R3, and the focal length of the imaging optical system is f, which can satisfy the following condition: 0<R3/f<2.0. Thereby, the surface shape and refractive power of the second lens can be adjusted to correct aberrations. Among them, the following conditions can also be satisfied: 0.15<R3/f<1.4. Among them, the following conditions can also be satisfied: 0.30<R3/f<0.90.

The thickness of the third lens on the optical axis is CT3, and the thickness of the fifth lens on the optical axis is CT5, which can satisfy the following conditions: 1.0<CT5/CT3; or CT5/CT3<10. In this way, the third lens and the fifth lens can cooperate with each other, which helps to balance the volume distribution of the object side end and the image side end of the imaging optical system. Among them, the following conditions can also be satisfied: 1.5<CT5/CT3. Among them, the following conditions can also be satisfied: 1.8<CT5/CT3. Among them, the following conditions can also be satisfied: 2.0<CT5/CT3. Among them, the following conditions can also be satisfied: 2.2<CT5/CT3. Among them, the following conditions can also be met: CT5/CT3<5.0. Among them, the following conditions can also be met: CT5/CT3<4.5. Among them, the following conditions can also be satisfied: 1.0<CT5/CT3<5.0. Among them, the following conditions can also be satisfied: 2.0<CT5/CT3<5.0.

The Abbe number of the second lens is V2, the Abbe number of the third lens is V3, and the Abbe number of the fourth lens is V4, which can satisfy the following conditions: 30.0<V2+V3+V4<120.0. In this way, the materials of the second lens, the third lens and the fourth lens can be matched with each other to further correct the chromatic aberration. Among them, the following conditions can also be satisfied: 35.0<V2+V3+V4<110.0. Among them, the following conditions can also be satisfied: 40.0<V2+V3+V4<100.0.

The Abbe number of the first lens is V1, the Abbe number of the second lens is V2, the Abbe number of the third lens is V3, the Abbe number of the fourth lens is V4, the Abbe number of the fifth lens is V5, The Abbe number of the sixth lens is V6, the Abbe number of the seventh lens is V7, the Abbe number of the eighth lens is V8, the Abbe number of the i-th lens is Vi, the refractive index of the first lens is N1, and the The refractive index of the second lens is N2, the refractive index of the third lens is N3, the refractive index of the fourth lens is N4, the refractive index of the fifth lens is N5, the refractive index of the sixth lens is N6, and the refractive index of the seventh lens is N6. is N7, the refractive index of the eighth lens is N8, the refractive index of the i-th lens is Ni, and the minimum value of Vi/Ni is (Vi/Ni)min, which can satisfy the following conditions: 6.0<(Vi/Ni)min< 12.0, where i=1, 2, 3, 4, 5, 6, 7, or 8. In this way, the material distribution of the imaging optical system can be adjusted, which is helpful for correcting aberrations and compressing the volume.

The curvature radius of the object-side surface of the fifth lens is R9, and the curvature radius of the image-side surface of the fifth lens is R10, which can satisfy the following conditions: -1.5<(R9+R10)/(R9-R10)<1.5. Thereby, the surface shape of the fifth lens can be adjusted to control the traveling direction of the light, which helps to achieve a balance between the viewing angle, the volume and the size of the imaging surface. Among them, the following conditions can also be satisfied: -1.1<(R9+R10)/(R9-R10)<1.1.

The distance on the optical axis from the object side surface of the first lens to the image side surface of the eighth lens is TD, and the thickness of the fifth lens on the optical axis is CT5, which can satisfy the following conditions: 3.0<TD/CT5<7.0. Thereby, the lens distribution can be adjusted, which contributes to the reduction of the overall length of the imaging optical system.

The focal length of the imaging optical system is f, the focal length of the second lens is f2, and the focal length of the third lens is f3, which can satisfy the following conditions: |f/f2|+|f/f3|<0.70. Thereby, the refractive power of the second lens and the third lens can cooperate with each other to correct the aberration.

The focal length of the imaging optical system is f, and the combined focal length of the first lens and the second lens is f12, which can satisfy the following conditions: 0.35<f/f12<0.75. In this way, the first lens and the second lens can cooperate with each other, which helps to compress the volume at the object side of the imaging optical system.

Half of the maximum angle of view in the imaging optical system is HFOV, which can satisfy the following conditions: 30.0[degrees]<HFOV<50.0[degrees]. Thereby, the optical system for imaging can have the characteristics of a wide viewing angle, and can avoid distortion caused by an excessively large viewing angle. Among them, the following conditions can also be satisfied: 35.0[degrees]<HFOV<45.0[degrees].

The Abbe number of the second lens is V2, and the refractive index of the second lens is N2, which can satisfy the following conditions: 6.0<V2/N2<15.0. Thereby, the material of the second lens can be adjusted to correct aberrations such as chromatic aberration.

The Abbe number of the sixth lens is V6, which can satisfy the following condition: 15.0<V6<50.0. Thereby, the material of the sixth lens can be adjusted to correct chromatic aberration.

The thickness of the first lens on the optical axis is CT1, and the thickness of the fifth lens on the optical axis is CT5, which can satisfy the following conditions: 1.1<CT5/CT1<2.0. Thereby, the lens distribution can be adjusted, which helps to compress the volume. Among them, the following conditions can also be satisfied: 1.2<CT5/CT1<1.8.

The distance on the optical axis from the object-side surface of the first lens to the image-side surface of the eighth lens is TD, and the focal length of the second lens is f2, which can satisfy the following conditions: -1.0<TD/f2<0.80. Thereby, it is helpful to adjust the lens and the refractive power distribution to compress the volume and correct the aberration. Among them, the following conditions can also be satisfied: -0.60<TD/f2<0.60.

The focal length of the imaging optical system is f, the focal length of the second lens is f2, the focal length of the third lens is f3, and the focal length of the fourth lens is f4, which can satisfy the following conditions: -0.90<f/f2+f/f3+ f/f4<0.20. In this way, the refractive powers of the second lens, the third lens and the fourth lens can be matched with each other to correct aberrations.

The focal length of the fifth lens is f5, and the thickness of the fifth lens on the optical axis is CT5, which can satisfy the following conditions: 1.0<f5/CT5<30. Thereby, the refractive power of the fifth lens can be adjusted to compress the volume. Among them, the following conditions can also be satisfied: 2.0<f5/CT5<20. Among them, the following conditions can also be satisfied: 3.0<f5/CT5<10.

The aperture value (F-number) of the imaging optical system is Fno, which can satisfy the following condition: 1.0<Fno<2.2. This allows a balance between aperture size and depth of field. Among them, the following conditions can also be satisfied: 1.2<Fno<1.8.

The maximum effective radius of the object-side surface of the first lens is Y11, and the maximum effective radius of the image-side surface of the eighth lens is Y82, which can satisfy the following conditions: 1.8<Y82/Y11<3.0. In this way, the outer diameter of the object-side end and the image-side end of the imaging optical system can be adjusted, which helps to achieve a balance among the viewing angle, volume, and imaging surface size. Referring to FIG. 25, a schematic diagram of parameters Y11 and Y82 according to the first embodiment of the present invention is shown.

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, which can satisfy the following conditions: -0.60<R1/R2<0.80. Thereby, the surface shape of the first lens can be adjusted, which is helpful for adjusting the traveling direction of the light to form a configuration with a wide viewing angle. Among them, the following conditions can also be satisfied: -0.30<R1/R2<0.70.

The focal length of the imaging optical system is f, the radius of curvature of the object-side surface of the sixth lens is R11, and the radius of curvature of the image-side surface of the sixth lens is R12, which can satisfy the following conditions: 2.5<f/|R11|+f/| R12|<7.5. In this way, the surface shape and refractive power of the sixth lens can be adjusted, which is helpful for correcting aberrations in cooperation with the fifth lens.

The Abbe number of the second lens is V2, and the Abbe number of the fourth lens is V4, which can satisfy the following condition: 20.0<V2+V4<65.0. In this way, the materials of the second lens and the fourth lens can be matched with each other to further correct the chromatic aberration. Among them, the following conditions can also be satisfied: 25.0<V2+V4<50.0.

The thickness of the first lens on the optical axis is CT1, the thickness of the second lens on the optical axis is CT2, the thickness of the third lens on the optical axis is CT3, the thickness of the fourth lens on the optical axis is CT4, and the thickness of the fourth lens on the optical axis is CT4. The thickness of the lens on the optical axis is CT5, which can satisfy the following conditions: 0.10<(CT2+CT3+CT4)/(CT1+CT5)<1.0. Thereby, the lens distribution can be adjusted to compress the volume of the imaging optical system. Among them, the following conditions can also be satisfied: 0.20<(CT2+CT3+CT4)/(CT1+CT5)<0.75.

The sum of the lens thicknesses on the optical axis of each lens in the imaging optical system is ΣCT, and the thickness of the fifth lens on the optical axis is CT5, which can satisfy the following conditions: 2.5<ΣCT/CT5<6.0. Thereby, the lens distribution can be adjusted to reduce the volume of the imaging optical system and contribute to the formation of a wide viewing angle configuration. Among them, the following conditions can also be satisfied: 3.0<ΣCT/CT5<5.0.

The distance from the object-side surface of the first lens to the imaging surface on the optical axis is TL, which can satisfy the following conditions: 3.0[mm]<TL<15.0[mm]. Thereby, the optical system for imaging can have an appropriate length to suit various applications.

The distance from the object-side surface of the first lens to the imaging surface on the optical axis is TL, and the focal length of the imaging optical system is f, which can satisfy the following conditions: 1.0<TL/f<1.6. In this way, a balance between viewing angle and overall length can be achieved.

The distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, and the maximum imaging height of the imaging optical system is 1 mgH (that is, half of the total diagonal length of the effective sensing area of the electronic photosensitive element), which can satisfy the following: Condition: 1.0<TL/ImgH<2.0. In this way, a balance can be achieved between the overall length and the size of the imaging plane.

The focal length of the imaging optical system 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 third lens is f3, the focal length of the fourth lens is f4, and the focal length of the fifth lens is f5. The focal length of the six lenses is f6, the focal length of the seventh lens is f7, and the focal length of the eighth lens is f8, which can satisfy at least one of the following conditions: 0.20<f/f1<1.0;-1.2<f/f2<1.2;-0.40 <f/f3<0.40; -1.0<f/f4<1.0; 0.20<f/f5<1.0; -1.2<f/f6<1.0; 0<f/f7<2.0; and -2.0<f/f8<0 . In this way, the refractive power of the lens can be adjusted, which helps to correct aberrations, compress the volume and adjust the viewing angle. Among them, at least one of the following conditions can also be satisfied: 0.30<f/f1<0.90; -0.40<f/f2<0.40; -0.30<f/f3<0.30; -0.80<f/f4<0.40; 0.35<f/f5 <0.90; -1.0<f/f6<0.50; 0.20<f/f7<1.8; and -1.7<f/f8<-0.30.

The focal length of the imaging optical system is f, and the combined focal length of the second lens and the third lens is f23, which can satisfy the following conditions: -0.40<f/f23<0.20. Thereby, the second lens and the third lens can cooperate with each other to correct the aberration.

The curvature radius of the object-side surface of the second lens is R3, and the curvature radius of the image-side surface of the second lens is R4, which can satisfy the following conditions: 0.50<R3/R4<2.0. Thereby, the surface shape of the second lens can be adjusted to correct aberrations such as astigmatism. Among them, the following conditions can also be satisfied: 0.70<R3/R4<1.5.

The above technical features of the imaging optical system of the present invention can be configured in combination to achieve corresponding effects.

In the imaging optical system disclosed in the present invention, the material of the lens can be glass or plastic. If the material of the lens is glass, the degree of freedom in the configuration of the refractive power of the imaging optical system can be increased, and the influence of the external temperature change on the imaging can be reduced, and the glass lens can be produced by techniques such as grinding or molding. If the lens material is plastic, the production cost can be effectively reduced. In addition, a spherical or aspherical surface (ASP) can be arranged on the mirror surface, wherein the spherical lens can reduce the difficulty of manufacturing, and if an aspherical surface is arranged on the mirror surface, more control variables can be obtained thereby to reduce aberrations, reduce The number of lenses can be reduced, and the total length of the imaging optical system of the present invention can be effectively reduced. Further, the aspheric surface can be made by plastic injection molding or molding glass lenses.

In the imaging optical system disclosed in the present invention, if the lens surface is an aspherical surface, it means that all or a part of the optically effective area of the lens surface is an aspherical surface.

In the imaging optical system disclosed in the present invention, additives can be selectively added to any (above) lens materials to change the transmittance of the lens to light in a specific wavelength band, thereby reducing stray light and color shift. For example: the additive can filter out the 600nm to 800nm band light in the system to help reduce excess red or infrared light; or it can filter out the 350nm to 450nm band light to reduce excess blue light or Ultraviolet light, therefore, the additive prevents the interference of certain wavelengths of light on the imaging. In addition, the additive can be uniformly mixed into the plastic and made into a lens by injection molding.

In the imaging optical system disclosed in the present invention, if the surface of the lens is convex and the position of the convex surface is not defined, it means that the convex surface can be located at the near optical axis of the surface of the lens; if the surface of the lens is concave and the position of the concave surface is not defined, then Indicates that the concave surface can be located near the optical axis of the lens surface. If the refractive power or focal length of the lens does not define its regional position, it means that the refractive power or focal length of the lens can be the refractive power or focal length of the lens at the near optical axis.

In the imaging optical system disclosed in the present invention, the inflection point of the lens surface refers to the boundary point where the curvature of the lens surface changes positively and negatively. The critical point (Critical Point) of the lens surface refers to the tangent point on the tangent line of the plane perpendicular to the optical axis and the tangent to the lens surface, and the critical point is not located on the optical axis.

In the imaging optical system disclosed in the present invention, the imaging surface of the imaging optical system can be a flat surface or a curved surface with any curvature, especially a curved surface with a concave surface facing the object side, depending on the corresponding electronic photosensitive element. .

In the imaging optical system disclosed in the present invention, more than one imaging correction element (flat field element, etc.) can be selectively arranged between the lens closest to the imaging surface and the imaging surface to achieve the effect of correcting the image (like curvature, etc.). The optical properties of the imaging correction element, such as curvature, thickness, refractive index, position, surface type (convex or concave, spherical or aspherical, diffractive surface and Fresnel surface, etc.) can be adjusted according to the needs of the imaging device. In general, a preferred imaging correction element configuration is a thin plano-concave element with a concave surface toward the object side disposed close to the imaging surface.

In the imaging optical system disclosed in the present invention, at least one diaphragm may be provided, which may be located before the first lens, between each lens or after the last lens. Field stop (FieldStop), etc., can be used to reduce stray light and help improve image quality.

In the imaging optical system disclosed in the present invention, the configuration of the aperture may be a front aperture or a central aperture. The front aperture means that the aperture is arranged between the subject and the first lens, and the middle aperture means that the aperture is arranged between the first lens and the imaging surface. If the aperture is a front aperture, the exit pupil (Exit Pupil) and the imaging surface can have a longer distance, so that it has a telecentric (Telecentric) effect, and it can increase the efficiency of the CCD or CMOS image receiving element of the electronic photosensitive element; A central aperture helps to expand the field of view of the imaging optical system.

In the present invention, a variable aperture element can be appropriately provided, and the variable aperture element can be a mechanical component or a light regulating element, which can control the size and shape of the aperture by electrical or electrical signals. The mechanical components may include movable parts such as blade sets and shielding plates; the light regulating element may include shielding materials such as filter elements, electrochromic materials, and liquid crystal layers. The variable aperture element can enhance the ability of image adjustment by controlling the amount of light entering the image or the exposure time. In addition, the variable aperture element can also be the aperture of the present invention, and the image quality, such as depth of field or exposure speed, can be adjusted by changing the aperture value.

According to the above-mentioned embodiments, specific embodiments are provided below and described in detail with reference to the accompanying drawings.

<First Embodiment>

Please refer to FIG. 1 to FIG. 2 , wherein FIG. 1 is a schematic diagram of the imaging device according to the first embodiment of the present invention, and FIG. 2 is the spherical aberration, astigmatism and distortion curves of the first embodiment from left to right. As can be seen from FIG. 1 , the imaging device includes an imaging optical system (not numbered otherwise) and an electronic photosensitive element 199 . The imaging optical system includes an aperture 100, a first lens 110, a second lens 120, a third lens 130, a diaphragm 101, a fourth lens 140, a fifth lens 150, a sixth lens 160, The seventh lens 170 , the eighth lens 180 , the filter element (Filter) 190 and the imaging surface 195 . The electronic photosensitive element 199 is arranged on the imaging surface 195 . The imaging optical system includes eight lenses ( 110 , 120 , 130 , 140 , 150 , 160 , 170 , and 180 ), and there are no other interpolated lenses between the lenses.

The first lens 110 has a positive refractive power and is made of plastic material. Its object-side surface 111 is convex at the near-optical axis, its image-side surface 112 is concave at the near-optical axis, and both surfaces are aspherical. The image side surface 112 has two points of inflection.

The second lens 120 has a positive refractive power and is made of plastic material. The object-side surface 121 is convex at the near-optical axis, the image-side surface 122 is concave at the near-optical axis, and both surfaces are aspherical. The side surface 121 has two inflection points, and like the side surface 122 has one inflection point.

The third lens 130 has a negative refractive power and is made of plastic material. Its object-side surface 131 is convex at the near-optical axis, its image-side surface 132 is concave at the near-optical axis, and both surfaces are aspherical. The side surface 131 has an inflection point, the image side surface 132 has an inverse point, the object side surface 131 has a critical point off-axis, and the image side surface 132 has a critical point off-axis.

The fourth lens 140 has a positive refractive power and is made of plastic material. Its object-side surface 141 is convex at the near-optical axis, and its image-side surface 142 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 141 has an inflection point, the image side surface 142 has an inflection point, the object side surface 141 has a critical point off-axis, and the image side surface 142 has a critical point off-axis.

The fifth lens 150 has a positive refractive power and is made of plastic material. Its object-side surface 151 is concave at the near-optical axis, and its image-side surface 152 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 151 has an inflection point, and like the side surface 152 has an inflection point.

The sixth lens 160 has a negative refractive power and is made of plastic material. Its object-side surface 161 is concave at the near optical axis, its image-side surface 162 is convex at the near optical axis, and both surfaces are aspherical. The side surface 161 has two inflection points, the image side surface 162 has two inflection points, and the image side surface 162 has a critical point off-axis.

The seventh lens 170 has a positive refractive power and is made of plastic material. Its object-side surface 171 is convex at the near-optical axis, and its image-side surface 172 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 171 has two inflection points, the image side surface 172 has an inflection point, the object side surface 171 has a critical point off-axis, and the image side surface 172 has a critical point off-axis.

The eighth lens 180 has a negative refractive power and is made of plastic material. Its object-side surface 181 is convex at the near-optical axis, and its image-side surface 182 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 181 has two inflection points, the image side surface 182 has three inflection points, the object side surface 181 has a critical point off-axis, and its image side surface 182 has a critical point off-axis .

The filter element 190 is made of glass, which is disposed between the eighth lens 180 and the imaging surface 195 and does not affect the focal length of the imaging optical system.

The curve equations of the aspheric surfaces of the above-mentioned lenses are expressed as follows:

X: Displacement parallel to the optical axis from the intersection of the aspheric surface and the optical axis to the point on the aspheric surface that is Y from the optical axis;

Y: the vertical distance between the point on the aspheric curve and the optical axis;

R: radius of curvature;

k: cone coefficient; and

Ai: i-th order aspheric coefficient.

In the imaging optical system of the first embodiment, the focal length of the imaging optical system is f, the aperture value of the imaging optical system is Fno, and the half of the maximum angle of view in the imaging optical system is HFOV, and the values are as follows: f=5.69 mm (mm), Fno=1.51, HFOV=39.4 degrees (deg.).

The Abbe number of the first lens 110 is V1, the Abbe number of the second lens 120 is V2, the Abbe number of the third lens 130 is V3, the Abbe number of the fourth lens 140 is V4, and the Abbe number of the fifth lens 150 is V4. The Abbe number of the sixth lens 160 is V6, the Abbe number of the seventh lens 170 is V7, the Abbe number of the eighth lens 180 is V8, the Abbe number of the i-th lens is Vi, the Abbe number of the ith lens is V The refractive index of the lens 110 is N1, the refractive index of the second lens 120 is N2, the refractive index of the third lens 130 is N3, the refractive index of the fourth lens 140 is N4, the refractive index of the fifth lens 150 is N5, and the refractive index of the sixth lens 150 is N5. The refractive index of the lens 160 is N6, the refractive index of the seventh lens 170 is N7, the refractive index of the eighth lens 180 is N8, the refractive index of the i-th lens is Ni, and the minimum value of Vi/Ni is (Vi/Ni)min , which satisfies the following condition: (Vi/Ni)min=10.90. In this embodiment, (Vi/Ni)min is equal to V3/N3, V4/N4 and V6/N6.

The Abbe number of the second lens 120 is V2, which satisfies the following condition: V2=20.4.

The Abbe number of the second lens 120 is V2, the Abbe number of the third lens 130 is V3, and the Abbe number of the fourth lens 140 is V4, which satisfy the following condition: V2+V3+V4=57.2.

The Abbe number of the second lens 120 is V2, and the Abbe number of the fourth lens 140 is V4, which satisfy the following condition: V2+V4=38.8.

The Abbe number of the second lens 120 is V2, and the refractive index of the second lens 120 is N2, which satisfies the following condition: V2/N2=12.29.

The Abbe number of the sixth lens 160 is V6, which satisfies the following condition: V6=18.4.

The sum of the lens thicknesses of the lenses on the optical axis in the imaging optical system is ΣCT, and the thickness of the fifth lens 150 on the optical axis is CT5, which satisfies the following condition: ΣCT/CT5=3.56. In this embodiment, ΣCT is the first lens 110 , the second lens 120 , the third lens 130 , the fourth lens 140 , the fifth lens 150 , the sixth lens 160 , the seventh lens 170 and the eighth lens 180 on the optical axis The sum of the thicknesses on .

The thickness of the first lens 110 on the optical axis is CT1, the thickness of the second lens 120 on the optical axis is CT2, the thickness of the third lens 130 on the optical axis is CT3, and the thickness of the fourth lens 140 on the optical axis is CT4, the thickness of the fifth lens 150 on the optical axis is CT5, which satisfies the following conditions: (CT2+CT3+CT4)/(CT1+CT5)=0.41.

The thickness of the second lens 120 on the optical axis is CT2, and the thickness of the third lens 130 on the optical axis is CT3, which satisfy the following conditions: CT3/CT2=1.00.

The thickness of the first lens 110 on the optical axis is CT1, and the thickness of the fifth lens 150 on the optical axis is CT5, which satisfy the following conditions: CT5/CT1=1.50.

The thickness of the third lens 130 on the optical axis is CT3, and the thickness of the fifth lens 150 on the optical axis is CT5, which satisfy the following conditions: CT5/CT3=4.25.

The thickness of the fifth lens 150 on the optical axis is CT5, and the thickness of the seventh lens 170 on the optical axis is CT7, which satisfy the following conditions: CT7/CT5=0.49.

The distance on the optical axis from the object-side surface 111 of the first lens to the image-side surface 182 of the eighth lens is TD, and the thickness of the fifth lens 150 on the optical axis is CT5, which satisfies the following condition: TD/CT5=5.64.

The distance on the optical axis from the object-side surface 111 of the first lens to the image-side surface 182 of the eighth lens is TD, and the focal length of the second lens 120 is f2, which satisfies the following condition: TD/f2=0.23.

The distance on the optical axis from the object-side surface 111 of the first lens to the imaging surface 195 is TL, which satisfies the following condition: TL=7.85 [mm].

The distance on the optical axis from the object-side surface 111 of the first lens to the imaging surface 195 is TL, and the focal length of the imaging optical system is f, which satisfies the following condition: TL/f=1.38.

The distance on the optical axis from the object-side surface 111 of the first lens to the imaging surface 195 is TL, and the maximum imaging height of the imaging optical system is ImgH, which satisfies the following condition: TL/ImgH=1.64.

The radius of curvature of the object-side surface 111 of the first lens is R1, and the radius of curvature of the image-side surface 112 of the first lens is R2, which satisfy the following condition: R1/R2=0.55.

The radius of curvature of the object-side surface 121 of the second lens is R3, and the focal length of the imaging optical system is f, which satisfies the following condition: R3/f=0.47.

The radius of curvature of the object-side surface 121 of the second lens is R3, and the radius of curvature of the image-side surface 122 of the second lens is R4, which satisfy the following condition: R3/R4=0.90.

The curvature radius of the object-side surface 151 of the fifth lens is R9, and the curvature radius of the image-side surface 152 of the fifth lens is R10, which satisfy the following conditions: (R9+R10)/(R9-R10)=1.03.

The focal length of the imaging optical system is f, and the focal length of the first lens 110 is f1, which satisfy the following condition: f/f1=0.42.

The focal length of the imaging optical system is f, and the focal length of the second lens 120 is f2, which satisfy the following condition: f/f2=0.20.

The focal length of the imaging optical system is f, the focal length of the second lens 120 is f2, and the focal length of the third lens 130 is f3, which satisfy the following conditions: |f/f2|+|f/f3|=0.40.

The focal length of the imaging optical system is f, the focal length of the second lens 120 is f2, the focal length of the third lens 130 is f3, and the focal length of the fourth lens 140 is f4, which satisfy the following conditions: f/f2+f/f3+f /f4=0.02.

The focal length of the imaging optical system is f, and the focal length of the third lens 130 is f3, which satisfy the following condition: f/f3=-0.20.

The focal length of the imaging optical system is f, and the focal length of the fourth lens 140 is f4, which satisfy the following condition: f/f4=0.02.

The focal length of the imaging optical system is f, and the focal length of the fifth lens 150 is f5, which satisfy the following condition: f/f5=0.73.

The focal length of the imaging optical system is f, and the focal length of the sixth lens 160 is f6, which satisfy the following condition: f/f6=−0.27.

The focal length of the imaging optical system is f, and the focal length of the seventh lens 170 is f7, which satisfy the following condition: f/f7=0.48.

The focal length of the imaging optical system is f, and the focal length of the eighth lens 180 is f8, which satisfy the following condition: f/f8=−0.66.

The focal length of the imaging optical system is f, and the combined focal length of the first lens 110 and the second lens 120 is f12, which satisfies the following condition: f/f12=0.62.

The focal length of the imaging optical system is f, and the combined focal length of the second lens 120 and the third lens 130 is f23, which satisfies the following condition: f/f23=0.02.

The focal length of the imaging optical system is f, the radius of curvature of the object-side surface 161 of the sixth lens is R11, and the radius of curvature of the image-side surface 162 of the sixth lens is R12, which satisfy the following conditions: f/|R11|+f/|R12 |=5.69.

The focal length of the fifth lens 150 is f5, and the thickness of the fifth lens 150 on the optical axis is CT5, which satisfies the following condition: f5/CT5=6.84.

The focal length of the first lens 110 is f1, and the focal length of the fifth lens 150 is f5, which satisfy the following condition: f5/f1=0.58.

The focal length of the seventh lens 170 is f7, and the focal length of the eighth lens 180 is f8, which satisfy the following condition: f8/f7=−0.73.

The maximum effective radius of the object-side surface 111 of the first lens is Y11, and the maximum effective radius of the image-side surface 182 of the eighth lens is Y82, which satisfy the following condition: Y82/Y11=2.12.

The vertical distance between the critical point and the optical axis of the object-side surface 171 of the seventh lens is Yc71, and the vertical distance between the critical point and the optical axis of the image-side surface 172 of the seventh lens is Yc72, which satisfy the following conditions: Yc72/Yc71=1.24 .

The vertical distance between the critical point of the image-side surface 182 of the eighth lens and the optical axis is Yc82, and the maximum effective radius of the image-side surface 182 of the eighth lens is Y82, which satisfies the following condition: Yc82/Y82=0.42.

Please refer to Table 1 and Table 2 below.

Table 1 shows the detailed structural data of the first embodiment of FIG. 1 , wherein the units of curvature radius, thickness and focal length are millimeters (mm), and surfaces 0 to 21 represent the surfaces from the object side to the image side in sequence. Table 2 shows the aspheric surface data in the first embodiment, wherein k is the cone surface coefficient in the aspheric surface curve equation, and A4 to A20 represent the 4th to 20th order aspheric surface coefficients of each surface. In addition, the following tables of the embodiments are schematic diagrams and aberration curves corresponding to the embodiments, and the definitions of the data in the tables are the same as those in Tables 1 and 2 of the first embodiment, and are not repeated here.

<Second Embodiment>

Please refer to FIG. 3 to FIG. 4 , wherein FIG. 3 is a schematic diagram of an imaging device according to a second embodiment of the present invention, and FIG. 4 is a graph of spherical aberration, astigmatism and distortion of the second embodiment from left to right. As can be seen from FIG. 3 , the imaging device includes an imaging optical system (not marked otherwise) and an electronic photosensitive element 299 . The imaging optical system includes a diaphragm 200, a first lens 210, a second lens 220, a diaphragm 201, a third lens 230, a diaphragm 202, a fourth lens 240, a fifth lens 250, a fourth lens 240, a fifth lens 250, Six lenses 260 , a seventh lens 270 , an eighth lens 280 , a filter element 290 and an imaging surface 295 . The electronic photosensitive element 299 is arranged on the imaging surface 295 . The imaging optical system includes eight lenses ( 210 , 220 , 230 , 240 , 250 , 260 , 270 , and 280 ), and there are no other interpolated lenses between the lenses.

The first lens 210 has a positive refractive power and is made of plastic material. Its object-side surface 211 is convex at the near-optical axis, and its image-side surface 212 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 212 has three inflection points, and like the side surface 212 has a critical point off-axis.

The second lens 220 has a negative refractive power and is made of plastic material. The object-side surface 221 is convex at the near optical axis, the image-side surface 222 is concave at the near optical axis, and both surfaces are aspherical. The side surface 221 has an inflection point, the image side surface 222 has an inflection point, and the object side surface 221 has a critical point off-axis.

The third lens 230 has a positive refractive power and is made of plastic material. Its object-side surface 231 is convex at the near optical axis, its image-side surface 232 is concave at the near optical axis, and both surfaces are aspherical. Side surface 231 has two inflection points, and like side surface 232 has two inflection points.

The fourth lens 240 has a positive refractive power and is made of plastic material. Its object-side surface 241 is convex at the near-optical axis, and its image-side surface 242 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 241 has an inflection point, the image side surface 242 has an inverse point, the object side surface 241 has a critical point off-axis, and the image side surface 242 has a critical point off-axis.

The fifth lens 250 has a positive refractive power and is made of plastic material. Its object-side surface 251 is concave at the near-optical axis, and its image-side surface 252 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 251 has an inflection point, and like the side surface 252 has an inflection point.

The sixth lens 260 has a negative refractive power and is made of plastic material. Its object-side surface 261 is concave at the near-optical axis, and its image-side surface 262 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 261 has two inflection points, the image side surface 262 has two inflection points, and the image side surface 262 has a critical point off-axis.

The seventh lens 270 has a positive refractive power and is made of plastic material. Its object-side surface 271 is convex at the near-optical axis, and its image-side surface 272 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 271 has two inflection points, the image side surface 272 has four inflection points, the object side surface 271 has a critical point off-axis, and its image side surface 272 has a critical point off-axis .

The eighth lens 280 has a negative refractive power and is made of plastic material. Its object-side surface 281 is convex at the near optical axis, and its image-side surface 282 is concave at the near optical axis. Both surfaces are aspherical. The side surface 281 has three inflection points, the image side surface 282 has an inflection point, the object side surface 281 has two critical points off-axis, and its image side surface 282 has a critical point off-axis .

The filter element 290 is made of glass, which is disposed between the eighth lens 280 and the imaging surface 295 and does not affect the focal length of the imaging optical system.

Please refer to Table 3 and Table 4 below.

In the second embodiment, the curve equation of the aspheric surface is expressed as in the form of the first embodiment. In addition, the definitions described in the following table are the same as the above-mentioned embodiments, and are not repeated here.

<Third Embodiment>

Please refer to FIGS. 5 to 6 , wherein FIG. 5 is a schematic diagram of an imaging device according to a third embodiment of the present invention, and FIG. 6 is a spherical aberration, astigmatism and distortion curve diagram of the third embodiment from left to right. As can be seen from FIG. 5 , the imaging device includes an imaging optical system (not numbered otherwise) and an electronic photosensitive element 399 . The imaging optical system includes an aperture 300, a first lens 310, a second lens 320, a third lens 330, a fourth lens 340, a fifth lens 350, a sixth lens 360, a diaphragm 301, The seventh lens 370 , the eighth lens 380 , the filter element 390 and the imaging surface 395 . The electronic photosensitive element 399 is arranged on the imaging surface 395 . The imaging optical system includes eight lenses ( 310 , 320 , 330 , 340 , 350 , 360 , 370 , and 380 ), and there are no other interpolated lenses between the lenses.

The first lens 310 has a positive refractive power and is made of plastic material. The object-side surface 311 is convex at the near optical axis, the image-side surface 312 is concave at the near optical axis, and both surfaces are aspherical.

The second lens 320 has a positive refractive power and is made of plastic material. The object-side surface 321 is convex at the near optical axis, the image-side surface 322 is concave at the near optical axis, and both surfaces are aspherical. The image side surface 322 has an inflection point.

The third lens 330 has a negative refractive power and is made of plastic material. Its object-side surface 331 is convex at the near optical axis, its image-side surface 332 is concave at the near optical axis, and both surfaces are aspherical. The side surface 331 has an inflection point, the image side surface 332 has two inflection points, the object side surface 331 has a critical point off-axis, and its image side surface 332 has two critical points off-axis .

The fourth lens 340 has a negative refractive power and is made of plastic material. Its object-side surface 341 is concave at the near-optical axis, and its image-side surface 342 is convex at the near-optical axis. Both surfaces are aspherical. Side surface 342 has three inflection points, and like side surface 342 has two critical points off-axis.

The fifth lens 350 has a positive refractive power and is made of glass, its object-side surface 351 is convex at the near-optical axis, its image-side surface 352 is convex at the near-optical axis, both surfaces are aspherical, and its object-side surface 352 is convex. The side surface 351 has two inflection points, the image side surface 352 has an inflection point, and the object side surface 351 has a critical point off-axis.

The sixth lens 360 has a positive refractive power and is made of plastic material. Its object-side surface 361 is concave at the near-optical axis, and its image-side surface 362 is convex at the near-optical axis. Both surfaces are aspherical. Side surface 361 has two inflection points, like side surface 362 has two inflection points, and like side surface 362 has a critical point off-axis.

The seventh lens 370 has a positive refractive power and is made of plastic material. Its object-side surface 371 is convex at the near optical axis, and its image-side surface 372 is concave at the near optical axis. Both surfaces are aspherical. The side surface 371 has three inflection points, the image side surface 372 has an inflection point, the object side surface 371 has a critical point off-axis, and its image side surface 372 has a critical point off-axis.

The eighth lens 380 has a negative refractive power and is made of plastic material. Its object-side surface 381 is convex at the near-optical axis, and its image-side surface 382 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 381 has four inflection points, the image side surface 382 has two inflection points, the object side surface 381 has a critical point off-axis, and its image side surface 382 has a critical point off-axis .

The filter element 390 is made of glass, which is disposed between the eighth lens 380 and the imaging surface 395 and does not affect the focal length of the imaging optical system.

Please refer to Table 5 and Table 6 below.

In the third embodiment, the curve equation of the aspheric surface is expressed as in the form of the first embodiment. In addition, the definitions described in the following table are the same as the above-mentioned embodiments, and are not repeated here.

<Fourth Embodiment>

Please refer to FIGS. 7 to 8 , wherein FIG. 7 is a schematic diagram of an imaging device according to a fourth embodiment of the present invention, and FIG. 8 is a graph of spherical aberration, astigmatism and distortion of the fourth embodiment from left to right. As can be seen from FIG. 7 , the imaging device includes an imaging optical system (not marked with another number) and an electronic photosensitive element 499 . The imaging optical system includes a diaphragm 400, a first lens 410, a second lens 420, a diaphragm 401, a third lens 430, a fourth lens 440, a diaphragm 402, a fifth lens 450, a diaphragm 402, a fifth lens 450, Six lenses 460 , a seventh lens 470 , an eighth lens 480 , a filter element 490 and an imaging surface 495 . Among them, the electronic photosensitive element 499 is arranged on the imaging surface 495 . The imaging optical system includes eight lenses ( 410 , 420 , 430 , 440 , 450 , 460 , 470 , and 480 ), and there are no other interpolated lenses between the lenses.

The first lens 410 has a positive refractive power and is made of plastic material. Its object-side surface 411 is convex at the near-optical axis, and its image-side surface 412 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 412 has two inflection points, and like the side surface 412 has a critical point off-axis.

The second lens 420 has a negative refractive power and is made of plastic material. The object-side surface 421 is convex at the near optical axis, the image-side surface 422 is concave at the near optical axis, and both surfaces are aspherical. The side surface 421 has two inflection points, and like the side surface 422 has one inflection point.

The third lens 430 has a positive refractive power and is made of plastic material. Its object-side surface 431 is convex at the near-optical axis, its image-side surface 432 is concave at the near-optical axis, and both surfaces are aspherical. The side surface 431 has an inflection point, the image side surface 432 has two inflection points, the object side surface 431 has a critical point off-axis, and the image side surface 432 has a critical point off-axis.

The fourth lens 440 has a negative refractive power and is made of plastic material. Its object-side surface 441 is convex at the near-optical axis, and its image-side surface 442 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 441 has three inflection points, the image side surface 442 has three inflection points, the object side surface 441 has three critical points off-axis, and its image side surface 442 has a critical point off-axis. point.

The fifth lens 450 has a positive refractive power and is made of plastic material. The object-side surface 451 is convex at the near optical axis, the image-side surface 452 is convex at the near optical axis, and both surfaces are aspherical. The image side surface 452 has an inflection point.

The sixth lens 460 has a negative refractive power and is made of plastic material. Its object-side surface 461 is convex at the near-optical axis, and its image-side surface 462 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 461 has an inflection point, the image side surface 462 has two inflection points, the object side surface 461 has a critical point off-axis, and its image side surface 462 has a critical point off-axis.

The seventh lens 470 has a positive refractive power and is made of plastic material. Its object-side surface 471 is convex at the near-optical axis, and its image-side surface 472 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 471 has three inflection points, the image side surface 472 has three inflection points, the object side surface 471 has a critical point off-axis, and its image side surface 472 has a critical point off-axis .

The eighth lens 480 has a negative refractive power and is made of plastic material. Its object-side surface 481 is concave at the near-optical axis, and its image-side surface 482 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 481 has an inflection point, the image side surface 482 has an inverse point, the object side surface 481 has a critical point off-axis, and the image side surface 482 has a critical point off-axis.

The material of the filter element 490 is glass, which is arranged between the eighth lens 480 and the imaging surface 495 and does not affect the focal length of the imaging optical system.

Please refer to Table 7 and Table 8 below.

In the fourth embodiment, the curve equation of the aspheric surface is expressed as in the first embodiment. In addition, the definitions described in the following table are the same as the above-mentioned embodiments, and are not repeated here.

<Fifth Embodiment>

Please refer to FIGS. 9 to 10 , wherein FIG. 9 is a schematic diagram of an imaging device according to a fifth embodiment of the present invention, and FIG. 10 is a spherical aberration, astigmatism and distortion curve diagram of the fifth embodiment from left to right. As can be seen from FIG. 9 , the imaging device includes an imaging optical system (not marked otherwise) and an electronic photosensitive element 599 . The imaging optical system includes a diaphragm 500, a first lens 510, a second lens 520, a diaphragm 501, a third lens 530, a diaphragm 502, a fourth lens 540, a fifth lens 550, a fourth lens 540, a fifth lens 550, Six lenses 560 , a seventh lens 570 , an eighth lens 580 , a filter element 590 and an imaging surface 595 . Among them, the electronic photosensitive element 599 is arranged on the imaging surface 595 . The imaging optical system includes eight lenses ( 510 , 520 , 530 , 540 , 550 , 560 , 570 , and 580 ), and there are no other interpolated lenses between the lenses.

The first lens 510 has a positive refractive power and is made of plastic material. Its object-side surface 511 is convex at the near-optical axis, and its image-side surface 512 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 512 has an inflection point, and like the side surface 512 has a critical point off-axis.

The second lens 520 has a negative refractive power and is made of plastic material. The object-side surface 521 is convex at the near-optical axis, and the image-side surface 522 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 521 has an inflection point, the image side surface 522 has an inflection point, and the object side surface 521 has a critical point off-axis.

The third lens 530 has a positive refractive power and is made of plastic material. Its object-side surface 531 is convex at the near-optical axis, its image-side surface 532 is concave at the near-optical axis, and both surfaces are aspherical. Side surface 531 has two inflection points, like side surface 532 has two inflection points, and like side surface 532 has two critical points off-axis.

The fourth lens 540 has a negative refractive power and is made of plastic material. Its object-side surface 541 is convex at the near-optical axis, and its image-side surface 542 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 541 has an inflection point, the image side surface 542 has an inverse point, the object side surface 541 has a critical point off-axis, and the image side surface 542 has a critical point off-axis.

The fifth lens 550 has a positive refractive power and is made of plastic material. Its object-side surface 551 is convex at the near-optical axis, and its image-side surface 552 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 551 has three inflection points, the image side surface 552 has an inflection point, and the object side surface 551 has a critical point off-axis.

The sixth lens 560 has a negative refractive power and is made of plastic material. Its object-side surface 561 is concave at the near-optical axis, and its image-side surface 562 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 561 has an inflection point, the image side surface 562 has two inflection points, the object side surface 561 has a critical point off-axis, and the image side surface 562 has a critical point off-axis.

The seventh lens 570 has a positive refractive power and is made of plastic material. Its object-side surface 571 is convex at the near-optical axis, and its image-side surface 572 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 571 has two inflection points, the image side surface 572 has four inflection points, the object side surface 571 has a critical point off-axis, and its image side surface 572 has a critical point off-axis .

The eighth lens 580 has a negative refractive power and is made of plastic material. Its object-side surface 581 is convex at the near-optical axis, and its image-side surface 582 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 581 has three inflection points, the image side surface 582 has an inflection point, the object side surface 581 has two critical points off-axis, and its image side surface 582 has a critical point off-axis .

The filter element 590 is made of glass, which is disposed between the eighth lens 580 and the imaging surface 595 and does not affect the focal length of the imaging optical system.

Please refer to Table 9 and Table 10 below.

In the fifth embodiment, the curve equation of the aspheric surface is expressed as in the first embodiment. In addition, the definitions described in the following table are the same as the above-mentioned embodiments, and are not repeated here.

<Sixth Embodiment>

Please refer to FIG. 11 to FIG. 12 , wherein FIG. 11 is a schematic diagram of the imaging device according to the sixth embodiment of the present invention, and FIG. 12 is the spherical aberration, astigmatism and distortion curves of the sixth embodiment from left to right. As can be seen from FIG. 11 , the imaging device includes an imaging optical system (not numbered otherwise) and an electronic photosensitive element 699 . The imaging optical system includes a diaphragm 600, a first lens 610, a second lens 620, a diaphragm 601, a third lens 630, a diaphragm 602, a fourth lens 640, a fifth lens 650, a fourth lens 640, a fifth lens 650, Six lenses 660 , a seventh lens 670 , an eighth lens 680 , a filter element 690 and an imaging surface 695 . The electronic photosensitive element 699 is arranged on the imaging surface 695 . The imaging optical system includes eight lenses ( 610 , 620 , 630 , 640 , 650 , 660 , 670 , 680 ), and there are no other interpolated lenses between the lenses.

The first lens 610 has a positive refractive power and is made of plastic material. The object-side surface 611 is convex at the near optical axis, the image-side surface 612 is concave at the near optical axis, and both surfaces are aspherical.

The second lens 620 has a negative refractive power and is made of plastic material. Its object-side surface 621 is convex at the near-optical axis, and its image-side surface 622 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 621 has an inflection point, the image side surface 622 has an inflection point, and the object side surface 621 has a critical point off-axis.

The third lens 630 has a positive refractive power and is made of plastic material. Its object-side surface 631 is convex at the near-optical axis, its image-side surface 632 is concave at the near-optical axis, and both surfaces are aspherical. Side surface 631 has two inflection points, like side surface 632 has two inflection points, and like side surface 632 has two critical points off-axis.

The fourth lens 640 has a negative refractive power and is made of plastic material. Its object-side surface 641 is convex at the near-optical axis, and its image-side surface 642 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 641 has an inflection point, the image side surface 642 has an inverse point, the object side surface 641 has a critical point off-axis, and the image side surface 642 has a critical point off-axis.

The fifth lens 650 has a positive refractive power and is made of plastic material. Its object-side surface 651 is convex at the near-optical axis, and its image-side surface 652 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 651 has two inflection points, the image side surface 652 has an inflection point, and the object side surface 651 has a critical point off-axis.

The sixth lens 660 has a negative refractive power and is made of plastic material. Its object-side surface 661 is concave at the near-optical axis, and its image-side surface 662 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 661 has two inflection points, its image side surface 662 has an inflection point, and its image side surface 662 has a critical point off-axis.

The seventh lens 670 has a positive refractive power and is made of plastic material. Its object-side surface 671 is convex at the near-optical axis, and its image-side surface 672 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 671 has two inflection points, the image side surface 672 has two inflection points, the object side surface 671 has a critical point off-axis, and its image side surface 672 has a critical point off-axis .

The eighth lens 680 has negative refractive power and is made of plastic material. Its object-side surface 681 is convex at the near-optical axis, and its image-side surface 682 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 681 has three inflection points, the image side surface 682 has three inflection points, the object side surface 681 has two critical points off-axis, and its image side surface 682 has a critical point off-axis. point.

The filter element 690 is made of glass, which is disposed between the eighth lens 680 and the imaging surface 695 and does not affect the focal length of the imaging optical system.

Please refer to Table 11 and Table 12 below.

In the sixth embodiment, the curve equation of the aspheric surface is expressed as in the first embodiment. In addition, the definitions described in the following table are the same as the above-mentioned embodiments, and are not repeated here.

<Seventh Embodiment>

Please refer to FIGS. 13 to 14 , wherein FIG. 13 is a schematic diagram of the imaging device according to the seventh embodiment of the present invention, and FIG. 14 is the spherical aberration, astigmatism and distortion curves of the seventh embodiment from left to right. As can be seen from FIG. 13 , the imaging device includes an imaging optical system (not numbered otherwise) and an electronic photosensitive element 799 . The imaging optical system includes an aperture 700, a first lens 710, a second lens 720, a third lens 730, a diaphragm 701, a fourth lens 740, a fifth lens 750, a sixth lens 760, The seventh lens 770 , the eighth lens 780 , the filter element 790 and the imaging surface 795 . Among them, the electronic photosensitive element 799 is arranged on the imaging surface 795 . The imaging optical system includes eight lenses ( 710 , 720 , 730 , 740 , 750 , 760 , 770 , and 780 ), and there are no other interpolated lenses between the lenses.

The first lens 710 has a positive refractive power and is made of plastic material. Its object-side surface 711 is convex at the near-optical axis, and its image-side surface 712 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 711 has an inflection point, the image side surface 712 has an inflection point, and the image side surface 712 has a critical point off-axis.

The second lens 720 has a negative refractive power and is made of plastic material. The object-side surface 721 is convex at the near-optical axis, and the image-side surface 722 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 721 has two inflection points, and like the side surface 722 has one inflection point.

The third lens 730 has a negative refractive power and is made of plastic material. Its object-side surface 731 is convex at the near-optical axis, its image-side surface 732 is concave at the near-optical axis, and both surfaces are aspherical. The side surface 731 has an inflection point, the image side surface 732 has an inverse point, the object side surface 731 has a critical point off-axis, and the image side surface 732 has a critical point off-axis.

The fourth lens 740 has a positive refractive power and is made of plastic material. Its object-side surface 741 is convex at the near-optical axis, and its image-side surface 742 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 741 has an inflection point, the image side surface 742 has an inverse point, the object side surface 741 has a critical point off-axis, and the image side surface 742 has a critical point off-axis.

The fifth lens 750 has a positive refractive power and is made of plastic material. Its object-side surface 751 is convex at the near-optical axis, and its image-side surface 752 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 751 has two inflection points, the image side surface 752 has an inflection point, and the object side surface 751 has a critical point off-axis.

The sixth lens 760 has negative refractive power and is made of plastic material. Its object-side surface 761 is concave at the near-optical axis, and its image-side surface 762 is convex at the near-optical axis. Both surfaces are aspherical. Side surface 761 has two inflection points, like side surface 762 has an inflection point, and like side surface 762 has a critical point off-axis.

The seventh lens 770 has a positive refractive power and is made of plastic material. Its object-side surface 771 is convex at the near-optical axis, and its image-side surface 772 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 771 has two inflection points, the image side surface 772 has two inflection points, the object side surface 771 has a critical point off-axis, and its image side surface 772 has a critical point off-axis .

The eighth lens 780 has a negative refractive power and is made of plastic material. Its object-side surface 781 is convex at the near-optical axis, and its image-side surface 782 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 781 has four inflection points, the image side surface 782 has three inflection points, the object side surface 781 has a critical point off-axis, and its image side surface 782 has a critical point off-axis .

The filter element 790 is made of glass, which is disposed between the eighth lens 780 and the imaging surface 795 and does not affect the focal length of the imaging optical system.

Please refer to Table 13 and Table 14 below.

In the seventh embodiment, the curve equation of the aspheric surface is expressed as in the first embodiment. In addition, the definitions described in the following table are the same as the above-mentioned embodiments, and are not repeated here.

<Eighth Embodiment>

Please refer to FIGS. 15 to 16 , wherein FIG. 15 is a schematic diagram of an imaging device according to an eighth embodiment of the present invention, and FIG. 16 is a graph of spherical aberration, astigmatism and distortion of the eighth embodiment from left to right. As can be seen from FIG. 15 , the imaging device includes an imaging optical system (not numbered otherwise) and an electronic photosensitive element 899 . The imaging optical system includes an aperture 800, a first lens 810, a second lens 820, a third lens 830, a diaphragm 801, a fourth lens 840, a fifth lens 850, a sixth lens 860, The seventh lens 870 , the eighth lens 880 , the filter element 890 and the imaging surface 895 . Among them, the electronic photosensitive element 899 is arranged on the imaging surface 895 . The imaging optical system includes eight lenses (810, 820, 830, 840, 850, 860, 870, 880), and there are no other interpolated lenses between the lenses.

The first lens 810 has a positive refractive power and is made of plastic material. Its object-side surface 811 is convex at the near-optical axis, and its image-side surface 812 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 811 has an inflection point, the image side surface 812 has an inflection point, and the image side surface 812 has a critical point off-axis.

The second lens 820 has a negative refractive power and is made of plastic material. Its object-side surface 821 is convex at the near-optical axis, its image-side surface 822 is concave at the near-optical axis, and both surfaces are aspherical. The side surface 821 has two inflection points, and like the side surface 822 has one inflection point.

The third lens 830 has a negative refractive power and is made of plastic material. Its object-side surface 831 is convex at the near-optical axis, its image-side surface 832 is concave at the near-optical axis, and both surfaces are aspherical. The side surface 831 has an inflection point, the image side surface 832 has an inverse point, the object side surface 831 has a critical point off-axis, and the image side surface 832 has a critical point off-axis.

The fourth lens 840 has a negative refractive power and is made of plastic material. Its object-side surface 841 is convex at the near-optical axis, and its image-side surface 842 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 841 has an inflection point, the image side surface 842 has an inverse point, the object side surface 841 has a critical point off-axis, and the image side surface 842 has a critical point off-axis.

The fifth lens 850 has a positive refractive power and is made of plastic material. Its object-side surface 851 is convex at the near-optical axis, and its image-side surface 852 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 851 has two inflection points, the image side surface 852 has an inflection point, and the object side surface 851 has a critical point off-axis.

The sixth lens 860 has a negative refractive power and is made of plastic material. Its object-side surface 861 is concave at the near-optical axis, and its image-side surface 862 is convex at the near-optical axis. Both surfaces are aspherical. Side surface 861 has two inflection points, like side surface 862 has an inflection point, and like side surface 862 has a critical point off-axis.

The seventh lens 870 has a positive refractive power and is made of plastic material. Its object-side surface 871 is convex at the near-optical axis, and its image-side surface 872 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 871 has two inflection points, the image side surface 872 has two inflection points, the object side surface 871 has a critical point off-axis, and its image side surface 872 has a critical point off-axis .

The eighth lens 880 has a negative refractive power and is made of plastic material. Its object-side surface 881 is convex at the near-optical axis, and its image-side surface 882 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 881 has four inflection points, the image side surface 882 has four inflection points, the object side surface 881 has a critical point off-axis, and its image side surface 882 has a critical point off-axis .

The filter element 890 is made of glass, which is disposed between the eighth lens 880 and the imaging surface 895 and does not affect the focal length of the imaging optical system.

Please refer to Table 15 and Table 16 below.

In the eighth embodiment, the curve equation of the aspheric surface is expressed as in the form of the first embodiment. In addition, the definitions described in the following table are the same as the above-mentioned embodiments, and are not repeated here.

<Ninth Embodiment>

Please refer to FIGS. 17 to 18 , wherein FIG. 17 is a schematic diagram of an imaging device according to a ninth embodiment of the present invention, and FIG. 18 is a graph of spherical aberration, astigmatism and distortion of the ninth embodiment from left to right. As can be seen from FIG. 17 , the imaging device includes an imaging optical system (not numbered otherwise) and an electronic photosensitive element 999 . The imaging optical system includes a diaphragm 900, a first lens 910, a second lens 920, a diaphragm 901, a third lens 930, a fourth lens 940, a diaphragm 902, a fifth lens 950, a diaphragm 902, a fifth lens 950, Six lenses 960 , a seventh lens 970 , an eighth lens 980 , a filter element 990 and an imaging surface 995 . Among them, the electronic photosensitive element 999 is arranged on the imaging surface 995 . The imaging optical system includes eight lenses ( 910 , 920 , 930 , 940 , 950 , 960 , 970 , and 980 ), and there are no other interpolated lenses between the lenses.

The first lens 910 has a positive refractive power and is made of plastic material. Its object-side surface 911 is convex at the near-optical axis, its image-side surface 912 is concave at the near-optical axis, and both surfaces are aspherical. The image side surface 912 has three inflection points.

The second lens 920 has a positive refractive power and is made of plastic material. Its object-side surface 921 is convex at the near-optical axis, and its image-side surface 922 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 922 has an inflection point, and like the side surface 922 has a critical point off-axis.

The third lens 930 has a positive refractive power and is made of plastic material. Its object-side surface 931 is concave at the near-optical axis, its image-side surface 932 is convex at the near-optical axis, and both surfaces are aspherical. Side surface 931 has two inflection points, like side surface 932 has three inflection points, and like side surface 932 has three critical points off-axis.

The fourth lens 940 has a negative refractive power and is made of plastic material. Its object-side surface 941 is concave at the near-optical axis, and its image-side surface 942 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 941 has three inflection points, the image side surface 942 has three inflection points, and the image side surface 942 has a critical point off-axis.

The fifth lens 950 has a positive refractive power and is made of plastic material. Its object-side surface 951 is convex at the near-optical axis, and its image-side surface 952 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 952 has two inflection points, and like the side surface 952 has a critical point off-axis.

The sixth lens 960 has negative refractive power and is made of plastic material. Its object-side surface 961 is convex at the near-optical axis, and its image-side surface 962 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 961 has an inflection point, the image side surface 962 has two inflection points, the object side surface 961 has a critical point off-axis, and the image side surface 962 has a critical point off-axis.

The seventh lens 970 has a positive refractive power and is made of plastic material. Its object-side surface 971 is convex at the near-optical axis, and its image-side surface 972 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 971 has two inflection points, the image side surface 972 has four inflection points, the object side surface 971 has a critical point off-axis, and its image side surface 972 has two critical points off-axis. point.

The eighth lens 980 has a negative refractive power and is made of plastic material. Its object-side surface 981 is concave at the near optical axis, and its image-side surface 982 is concave at the near optical axis. Both surfaces are aspherical. The side surface 981 has an inflection point, the image side surface 982 has an inflection point, and the image side surface 982 has a critical point off-axis.

The filter element 990 is made of glass, which is disposed between the eighth lens 980 and the imaging surface 995 and does not affect the focal length of the imaging optical system.

Please refer to Table 17 and Table 18 below.

In the ninth embodiment, the curve equation of the aspheric surface is expressed as in the form of the first embodiment. In addition, the definitions described in the following table are the same as the above-mentioned embodiments, and are not repeated here.

<Tenth Embodiment>

Please refer to FIGS. 19 to 20 , wherein FIG. 19 is a schematic diagram of an imaging device according to a tenth embodiment of the present invention, and FIG. 20 is a graph of spherical aberration, astigmatism and distortion of the tenth embodiment from left to right. As can be seen from FIG. 19 , the imaging device includes an imaging optical system (not marked otherwise) and an electronic photosensitive element 1099 . The imaging optical system includes an aperture 1000, a first lens 1010, a second lens 1020, a third lens 1030, a diaphragm 1001, a fourth lens 1040, a fifth lens 1050, a sixth lens 1060, The seventh lens 1070 , the eighth lens 1080 , the filter element 1090 and the imaging surface 1095 . Among them, the electronic photosensitive element 1099 is arranged on the imaging surface 1095 . The imaging optical system includes eight lenses (1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080), and there are no other interpolated lenses between the lenses.

The first lens 1010 has a positive refractive power and is made of plastic material. Its object-side surface 1011 is convex at the near-optical axis, and its image-side surface 1012 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 1011 has an inflection point, and like the side surface 1012 has an inflection point.

The second lens 1020 has a positive refractive power and is made of plastic material. The object-side surface 1021 is convex at the near optical axis, the image-side surface 1022 is concave at the near optical axis, and both surfaces are aspherical.

The third lens 1030 has a negative refractive power and is made of plastic material. The object-side surface 1031 is convex at the near optical axis, the image-side surface 1032 is concave at the near optical axis, and both surfaces are aspherical.

The fourth lens 1040 has a negative refractive power and is made of plastic material. Its object-side surface 1041 is convex at the near optical axis, and its image-side surface 1042 is concave at the near optical axis. Both surfaces are aspherical. The side surface 1041 has an inflection point, the image side surface 1042 has two inflection points, the object side surface 1041 has a critical point off-axis, and its image side surface 1042 has two critical points off-axis .

The fifth lens 1050 has a positive refractive power and is made of plastic material. Its object-side surface 1051 is convex at the near-optical axis, and its image-side surface 1052 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 1051 has two inflection points, the image side surface 1052 has an inflection point, and the object side surface 1051 has two critical points off-axis.

The sixth lens 1060 has a positive refractive power and is made of plastic material. Its object-side surface 1061 is convex at the near-optical axis, and its image-side surface 1062 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 1061 has two inflection points, the image side surface 1062 has two inflection points, and the object side surface 1061 has a critical point off-axis.

The seventh lens 1070 has a positive refractive power and is made of plastic material. Its object-side surface 1071 is convex at the near-optical axis, and its image-side surface 1072 is convex at the near-optical axis. Both surfaces are aspherical. The side surface 1071 has two inflection points, the image side surface 1072 has three inflection points, the object side surface 1071 has a critical point off-axis, and its image side surface 1072 has two critical points off-axis point.

The eighth lens 1080 has a negative refractive power and is made of plastic material. Its object-side surface 1081 is concave at the near-optical axis, and its image-side surface 1082 is concave at the near-optical axis. Both surfaces are aspherical. The side surface 1081 has an inflection point, the image-side surface 1082 has two inflection points, the object-side surface 1081 has a critical point off-axis, and the image-side surface 1082 has a critical point off-axis.

The filter element 1090 is made of glass, which is disposed between the eighth lens 1080 and the imaging surface 1095 and does not affect the focal length of the imaging optical system.

Please refer to Table 19 and Table 20 below.

In the tenth embodiment, the curve equation of the aspheric surface is expressed as in the first embodiment. In addition, the definitions described in the following table are the same as the above-mentioned embodiments, and are not repeated here.

<Eleventh Embodiment>

Please refer to FIG. 21 , which is a perspective view of an imaging device according to an eleventh embodiment of the present invention. In this embodiment, the imaging device 10 is a camera module. The imaging device 10 includes an imaging lens 11 , a driving device 12 , an electronic photosensitive element 13 and an image stabilization module 14 . The imaging lens 11 includes the imaging optical system of the above-mentioned first embodiment, a lens barrel (not marked) for carrying the imaging optical system, and a support device (Holder Member, not marked). The imaging lens 11 can also be modified with other configurations. The imaging optical system of the embodiment is not limited to the present invention. The imaging device 10 uses the imaging lens 11 to condense light to generate an image, and cooperates with the driving device 12 to focus the image, and finally images the image on the electronic photosensitive element 13 and can be output as image data.

The driving device 12 may have an auto-focus (Auto-Focus) function, and its driving method may use, for example, a voice coil motor (Voice Coil Motor, VCM), a micro electro-mechanical system (Micro Electro-Mechanical Systems, MEMS), a piezoelectric system (Piezoelectric) , and memory alloy (Shape Memory Alloy) and other drive systems. The driving device 12 can enable the imaging lens 11 to obtain a better imaging position, and can provide clear images of the subject under different object distances. In addition, the imaging device 10 is equipped with an electronic photosensitive element 13 (eg, CMOS, CCD) with good brightness and low noise, which is disposed on the imaging surface of the imaging optical system, which can truly present the good imaging quality of the imaging optical system.

The image stabilization module 14 is, for example, an accelerometer, a gyroscope, or a Hall Effect Sensor. The driving device 12 can be used together with the image stabilization module 14 as an Optical Image Stabilization (OIS) device, which can compensate for the blurred image caused by shaking at the moment of shooting by adjusting the changes of the different axes of the imaging lens 11, or use the image The image compensation technology in the software provides Electronic Image Stabilization (EIS), which further improves the imaging quality of dynamic and low-light scenes.

<Twelfth Embodiment>

Please refer to FIGS. 22 to 24 , wherein FIG. 22 is a perspective view of one side of an electronic device according to a twelfth embodiment of the present invention, FIG. 23 is a perspective view of the other side of the electronic device of FIG. 22 , and FIG. 24 is a system block diagram of the electronic device of FIG. 22 .

In this embodiment, the electronic device 20 is a smart phone. The electronic device 20 includes the imaging device 10 of the eleventh embodiment, the imaging device 10a, the imaging device 10b, a flash module 21, a focus assist module 22, an image signal processor 23 (Image Signal Processor), a user interface 24, and an image Software processor 25. The imaging device 10 , the imaging device 10 a and the imaging device 10 b face the same direction and are all single focus. Moreover, the image capturing device 10a and the image capturing device 10b both have a similar structure and configuration as the image capturing device 10 . Specifically, the imaging device 10a and the imaging device 10b each include an imaging lens, a driving device, an electronic photosensitive element, and an image stabilization module. The imaging lenses of the imaging device 10a and the imaging device 10b each include a lens system group, a lens barrel for carrying the lens system group, and a support device.

The imaging device 10, the imaging device 10a, and the imaging device 10b in this embodiment have different viewing angles. Specifically, the imaging device 10 is a wide-angle imaging device, the imaging device 10a is a telephoto imaging device, and the imaging device 10b is an ultra-wide-angle imaging device, and the maximum viewing angle of the imaging device 10 is between the between the maximum viewing angles of the imaging device 10a and the imaging device 10b. The imaging device 10 , the imaging device 10 a and the imaging device 10 b in this embodiment have different viewing angles, so that the electronic device 20 can provide different magnifications to achieve the shooting effect of optical zoom. The above-mentioned electronic device 20 includes a plurality of image capturing devices 10 , 10 a and 10 b as an example, but the number and configuration of the image capturing devices are not intended to limit the present invention.

When the user shoots the subject 26 , the electronic device 20 uses the imaging device 10 , the imaging device 10 a or the imaging device 10 b to focus and capture the image, activate the flash module 21 to fill in the light, and use the object provided by the focus assist module 22 to capture the image. The object distance information of the object 26 is used for fast focusing, and the image signal processor 23 performs image optimization processing to further improve the image quality generated by the imaging optical system. The focusing assisting module 22 can use an infrared or laser focusing assisting system to achieve fast focusing. The user interface 24 can use a touch screen or a physical shooting button, and cooperate with the diversified functions of the image software processor 25 to perform image shooting and image processing. The image processed by the image software processor 25 can be displayed on the user interface 24 .

The imaging device 10 of the present invention is not limited to be applied to a smart phone. The imaging device 10 can be applied to a moving focus system as required, and has the characteristics of excellent aberration correction and good imaging quality. For example, the imaging device 10 can be applied in various aspects to three-dimensional (3D) image capture, digital cameras, mobile devices, tablet computers, smart TVs, network monitoring equipment, driving recorders, reversing developing devices, multi-lens devices, identification In electronic devices such as systems, somatosensory game consoles and wearable devices. The above-mentioned electronic device is only an example to illustrate the practical application of the present invention, and is not intended to limit the scope of application of the imaging device of the present invention.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the scope defined by the appended claims.

Claims (21)

1. An optical system for image capture, comprising eight lenses, 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, wherein the eight lenses respectively have an object side surface facing the object side direction and an image side surface facing the image side direction;

the first lens element with positive refractive power has a convex object-side surface at a paraxial region, the fifth lens element with positive refractive power has a convex object-side surface at a paraxial region, the seventh lens element with a concave image-side surface at a paraxial region, the eighth lens element with a concave image-side surface at a paraxial region, and at least one surface of at least one lens element in the imaging optical system has at least one critical point at an off-axis region;

wherein an abbe number of the second lens element is V2, a focal length of the imaging optical system is f, a focal length of the first lens element is f1, a focal length of the fifth lens element is f5, a focal length of the seventh lens element is f7, a focal length of the eighth lens element is f8, a radius of curvature of an object-side surface of the second lens element is R3, 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 axial thickness of the second lens element is CT2, an axial thickness of the third lens element is CT3, and the following conditions are satisfied:

10.0<V2<50.0；

0<f5/f1<9.5；

-7.5<f8/f7<-0.55；

0<R3/f<2.0；

2.5< f/| R11| + f/| R12| < 7.5; and

0.10<CT3/CT2<1.5。

2. the imaging optical system according to claim 1, wherein the abbe number of the second lens is V2, which satisfies the following condition:

12.0<V2<30.0。

3. the imaging optical system according to claim 1, wherein a focal length of the seventh lens element is f7, and a focal length of the eighth lens element is f8, and the following conditions are satisfied:

-1.5<f8/f7<-0.65。

4. the imaging optical system according to claim 1, wherein the abbe number of the first lens is V1, the abbe number of the second lens is V2, the abbe number of the third lens is V3, the abbe number of the fourth lens is V4, the abbe number of the fifth lens is V5, the abbe number of the sixth lens is V6, the abbe number of the seventh lens is V7, the abbe number of the eighth lens is V8, the abbe number of the i-th lens is Vi, the refractive index of the first lens is N1, the refractive index of the second lens is N2, the refractive index of the third lens is N3, the refractive index of the fourth lens is N4, the refractive index of the fifth lens is N5, the refractive index of the sixth lens is N6, the refractive index of the seventh lens is N7, the refractive index of the eighth lens is N8, the refractive index of the fifth lens is N5, the refractive index of the sixth lens is Ni/min (Ni/Ni), it satisfies the following conditions:

6.0< (Vi/Ni) min <12.0, wherein i ═ 1, 2, 3, 4, 5, 6, 7, or 8.

5. The imaging optical system according to claim 1, wherein a focal length of the imaging optical system is f, and a combined focal length of the first lens and the second lens is f12, and the following conditions are satisfied:

0.35<f/f12<0.75。

6. the imaging optical system according to claim 1, wherein the seventh lens element with positive refractive power, the eighth lens element with negative refractive power, and the object-side surface of the eighth lens element being concave at a paraxial region.

7. The imaging optical system of claim 1, wherein an object-side surface of the sixth lens element is convex at a paraxial region thereof, an image-side surface of the sixth lens element is concave at a paraxial region thereof, and at least one surface of the sixth lens element has at least one critical point at an off-axis region thereof.

8. An optical system for image capture, comprising eight lenses, 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, wherein the eight lenses respectively have an object side surface facing the object side direction and an image side surface facing the image side direction;

the first lens element with positive refractive power has a convex object-side surface at a paraxial region, the fifth lens element with positive refractive power has a convex object-side surface at a paraxial region, the seventh lens element with a concave image-side surface at a paraxial region, the eighth lens element with a concave image-side surface at a paraxial region, and at least one surface of at least one lens element in the imaging optical system has at least one critical point at an off-axis region;

wherein an abbe number of the second lens element is V2, a focal length of the imaging optical system is f, a focal length of the first lens element is f1, a focal length of the fifth lens element is f5, a focal length of the seventh lens element is f7, a focal length of the eighth lens element is f8, a radius of curvature of the object-side surface of the second lens element is R3, a radius of curvature of the object-side surface of the fifth lens element is R9, a radius of curvature of the image-side surface of the fifth lens element is R10, a radius of curvature of the object-side surface of the sixth lens element is R11, a radius of curvature of the image-side surface of the sixth lens element is R12, and the following conditions are satisfied:

10.0<V2<50.0；

0<f5/f1<9.5；

-7.5<f8/f7<-0.55；

0<R3/f<2.0；

2.5< f/| R11| + f/| R12| < 7.5; and

-1.5<(R9+R10)/(R9-R10)<1.5。

9. the imaging optical system according to claim 8, wherein the abbe number of the second lens is V2, which satisfies the following condition:

11.0<V2<40.0。

10. the imaging optical system according to claim 8, wherein a focal length of the seventh lens element is f7, and a focal length of the eighth lens element is f8, and the following conditions are satisfied:

-4.0<f8/f7<-0.60。

11. the imaging optical system according to claim 8, wherein a radius of curvature of the object-side surface of the fifth lens element is R9, and a radius of curvature of the image-side surface of the fifth lens element is R10, and the following conditions are satisfied:

-1.1<(R9+R10)/(R9-R10)<1.1。

12. the imaging optical system according to claim 8, wherein the abbe number of the second lens is V2, the abbe number of the third lens is V3, and the abbe number of the fourth lens is V4, and the following conditions are satisfied:

40.0<V2+V3+V4<100.0。

13. the imaging optical system according to claim 8, wherein a focal length of the imaging optical system is f, and a combined focal length of the first lens and the second lens is f12, and the following conditions are satisfied:

0.35<f/f12<0.75。

14. the imaging optical system of claim 8, wherein a vertical distance between a critical point of the object-side surface of the seventh lens element and an optical axis is Yc71, a vertical distance between a critical point of the image-side surface of the seventh lens element and the optical axis is Yc72, and at least one critical point of each of the object-side surface and the image-side surface of the seventh lens element at off-axis satisfies the following condition:

0.80<Yc72/Yc71<1.5。

15. an optical system for image capture, comprising eight lenses, 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, wherein the eight lenses respectively have an object side surface facing the object side direction and an image side surface facing the image side direction;

the first lens element with positive refractive power has a convex object-side surface at a paraxial region, the fifth lens element with positive refractive power has a convex object-side surface at a paraxial region, the seventh lens element with a concave image-side surface at a paraxial region, the eighth lens element with a concave image-side surface at a paraxial region, and at least one surface of at least one lens element in the imaging optical system has at least one critical point at an off-axis region;

wherein an abbe number of the second lens element is V2, a focal length of the imaging optical system is f, a focal length of the first lens element is f1, a focal length of the third lens element is f3, a focal length of the fifth lens element is f5, a focal length of the seventh lens element is f7, a focal length of the eighth lens element is f8, a radius of curvature of the object-side surface of the second lens element is R3, a radius of curvature of the object-side surface of the sixth lens element is R11, and a radius of curvature of the image-side surface of the sixth lens element is R12, and the following conditions are satisfied:

10.0<V2<50.0；

0<f5/f1<9.5；

-7.5<f8/f7<-0.55；

0<R3/f<2.0；

2.5< f/| R11| + f/| R12| < 7.5; and

-0.40<f/f3<0.40。

16. the imaging optical system according to claim 15, wherein the abbe number of the second lens is V2, which satisfies the following condition:

11.0<V2<40.0。

17. the imaging optical system according to claim 15, wherein a focal length of the seventh lens element is f7, and a focal length of the eighth lens element is f8, and the following conditions are satisfied:

-4.0<f8/f7<-0.60。

18. the imaging optical system according to claim 15, wherein a focal length of the imaging optical system is f, and a focal length of the third lens is f3, and the following conditions are satisfied:

-0.30<f/f3<0.30。

19. the imaging optical system according to claim 15, wherein a focal length of the imaging optical system is f, and a combined focal length of the first lens and the second lens is f12, and the following conditions are satisfied:

0.35<f/f12<0.75。

20. the imaging optical system according to claim 15, wherein an aperture value of the imaging optical system is Fno, and half of a maximum field angle in the imaging optical system is HFOV, and the following conditions are satisfied:

1.0< Fno < 2.2; and

30.0 degrees < HFOV <50.0 degrees.

21. The imaging optical system according to claim 15, wherein at least one surface of each of at least three lenses in the imaging optical system has at least one inflection point;

wherein a vertical distance between a critical point of the image-side surface of the eighth lens element and the optical axis is Yc82, a maximum effective radius of the image-side surface of the eighth lens element is Y82, and at least one critical point of the image-side surface of the eighth lens element at the off-axis position satisfies the following condition:

0.20<Yc82/Y82<0.60。

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