KR20210049073A - Optical system - Google Patents

Abstract

An imaging optical system according to an embodiment of the present invention, in order from an object side, comprises: a first lens having positive refractive power and having a convex object side surface; a second lens having negative refractive power and having a convex object side surface and a concave image side surface; a third lens having positive refractive power and having a convex image side surface; a fourth lens having refractive power; a fifth lens having refractive power; and a sixth lens having refractive power. When the distance from the object side surface of the first lens to the image surface is TTL, 1.1 < TTL/f < 1.35 is satisfied. When the Abbe's number of the first lens is v1 and the Abbe's number of the second lens is v2, v1-v2 > 20 can be satisfied.

Description

Optical system {Optical system}

The present invention relates to an optical system.

Recently, portable terminals are equipped with cameras to enable video calls and photographs. In addition, as functions occupied by cameras in portable terminals are gradually increasing, demands for high resolution and high performance of cameras for portable terminals are gradually increasing.

However, since portable terminals are gradually miniaturized or lightened, there is a limit to implementing a high-resolution and high-performance camera.

In order to solve this problem, recently, the lens of the camera is made of a plastic material that is lighter than that of glass, and a lens module is composed of five or more lenses to realize high resolution.

An object according to an embodiment of the present invention is to provide an optical system capable of improving an aberration improvement effect and implementing a bright and high resolution.

An optical system according to an embodiment of the present invention includes: a first lens having positive refractive power in order from an object side, and having a convex object side surface; A second lens having negative refractive power, a convex object-side surface and a concave image-side surface; A third lens having positive refractive power and having a convex image-side surface; A fourth lens having refractive power; A fifth lens having refractive power; And a sixth lens having refractive power, wherein when the distance from the object-side surface of the first lens to the image pickup surface is TTL, 1.1 <TTL/f <1.35 is satisfied, and the Abbe number of the first lens When v1 and the Abbe number of the second lens are v2, v1-v2> 20 may be satisfied.

According to the optical system according to an exemplary embodiment of the present invention, an aberration improvement effect can be improved, and bright and high resolution can be realized.

1 is a configuration diagram of an optical system according to a first embodiment of the present invention,
2 is a curve showing aberration characteristics of the optical system shown in FIG. 1,
3 is a table showing the characteristics of each lens of the optical system shown in FIG. 1,
4 is a table showing aspheric coefficients of each lens of the optical system shown in FIG. 1,
5 is a configuration diagram of an optical system according to a second embodiment of the present invention,
6 is a curve showing aberration characteristics of the optical system shown in FIG. 5,
7 is a table showing the characteristics of each lens of the optical system shown in FIG. 5,
8 is a table showing aspheric coefficients of each lens of the optical system shown in FIG. 5,
9 is a configuration diagram of an optical system according to a third embodiment of the present invention,
10 is a curve showing aberration characteristics of the optical system shown in FIG. 9,
11 is a table showing the characteristics of each lens of the optical system shown in FIG. 9,
12 is a table showing aspheric coefficients of each lens of the optical system shown in FIG. 9,
13 is a configuration diagram of an optical system according to a fourth embodiment of the present invention,
14 is a curve showing aberration characteristics of the optical system shown in FIG. 13,
15 is a table showing the characteristics of each lens of the optical system shown in FIG. 13,
16 is a table showing aspheric coefficients of each lens of the optical system shown in FIG. 13,
FIG. 17 is a view showing an angle between a tangent line at an end of an effective mirror of an image-side surface of a second lens and an image sensor in the optical system illustrated in FIG. 1.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention can add, change, or delete other elements within the scope of the same idea, Other embodiments included within the scope of the inventive concept may be easily proposed, but this will also be said to be included within the scope of the inventive concept of the present application.

In addition, components having the same function within the scope of the same idea shown in the drawings of each embodiment will be described using the same reference numerals.

In the following lens configuration diagram, the thickness, size, and shape of the lens are somewhat exaggerated for explanation, and in particular, the shape of the spherical or aspherical surface suggested in the lens configuration diagram is presented as an example, but is not limited thereto.

In addition, the first lens means the lens closest to the object side, and the sixth lens means the lens closest to the image side.

Further, the front means a side closer to the object side in the imaging optical system, and the rear side means the side closer to the image sensor or the image side in the imaging optical system. In addition, in each lens, the first surface means a surface close to the object side (or object side surface), and the second surface means a surface close to the image side (or image side surface). In addition, in the present specification, the values for the radius of curvature and thickness of the lens are all in mm.

In addition, the paraxial region (近軸領域) refers to a very narrow area near the optical axis, for example, may mean a region where the distance from the optical axis is zero.

The optical system according to an embodiment of the present invention includes six lenses.

That is, the optical system according to an embodiment of the present invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens.

However, the optical system according to an embodiment of the present invention is not composed of only six lenses, and may further include other components as necessary. For example, the optical system may further include a stop for adjusting the amount of light. In addition, the optical system may further include an infrared cut filter for blocking infrared rays. In addition, the optical system may further include an image sensor for converting an image of an incident subject into an electric signal. In addition, the optical system may further include a gap maintaining member for adjusting a distance between the lens and the lens.

The first to sixth lenses constituting the optical system according to an exemplary embodiment of the present invention may be made of a plastic material.

In addition, at least one of the first to sixth lenses has an aspherical surface. In addition, each of the first to sixth lenses may have at least one aspherical surface.

That is, at least one of the first and second surfaces of the first to sixth lenses may be aspherical. Here, aspherical surfaces of the first to sixth lenses are expressed by Equation 1.

In Equation 1, c is the curvature (the reciprocal of the radius of curvature) at the vertex of the lens, K is the Konig constant, and Y is the distance in the direction perpendicular to the optical axis. In addition, constants A to F mean aspheric coefficients. And Z represents the distance from the apex of the lens in the direction of the optical axis.

The optical system including the first to sixth lenses has positive/negative/positive/positive or negative/negative/positive refractive power in order from the object side.

The optical system configured as described above can improve optical performance by improving aberrations. In addition, in the optical system configured as described above, all six lenses may be made of a plastic material.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 1.

[Conditional Expression 1]

0.2 <SD/f <0.6

In Conditional Expression 1, SD is the radius of the aperture, and f is the total focal length of the optical system.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 2.

[Conditional Expression 2]

1.1 <TTL/f <1.35

In Conditional Equation 2, TTL is a distance from the object-side surface of the first lens to the image sensor, and f is the total focal length of the optical system.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 3.

[Conditional Expression 3]

1.0 <|r9|/f <40

In Conditional Expression 3, f is the total focal length of the optical system, and r9 is the radius of curvature of the object-side surface of the fifth lens.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 4.

[Conditional Expression 4]

|v5-v6| > 20

In Conditional Expression 4, the Abbe number of the fifth lens, v6 is the Abbe number of the sixth lens.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 5.

[Conditional Expression 5]

v1-v2> 20

In Conditional Expression 5, v1 is the Abbe number of the first lens, and v2 is the Abbe number of the second lens.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 6.

[Conditional Expression 6]

1.3 <f/f1 <1.6

In Conditional Equation 6, f is the total focal length of the optical system, and f1 is the focal length of the first lens.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 7.

[Conditional Expression 7]

0.1 <f/f3 <0.3

In Conditional Expression 7, f is the total focal length of the optical system, and f3 is the focal length of the third lens.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 8.

[Conditional Expression 8]

0.2 <|f/f5| <0.4

In Conditional Equation 8, f is the total focal length of the optical system, and f5 is the focal length of the fifth lens.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 9.

[Conditional Expression 9]

0 <f1/f3 <0.2

In Conditional Expression 9, f1 is a focal length of the first lens, and f3 is a focal length of the third lens.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 10.

[Conditional Expression 10]

2 <|f/f1| + |f/f2| <2.5

In Conditional Equation 10, f is the total focal length of the optical system, f1 is the focal length of the first lens, and f2 is the focal length of the second lens.

The optical system according to an embodiment of the present invention satisfies Conditional Equation 11.

[Conditional Expression 11]

0.1 <|f/f3| + |f/f4| <0.4

In Conditional Equation 11, f is the total focal length of the optical system, f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 12.

[Conditional Expression 12]

0.3 <|f/f5| + |f/f6| <0.6

In Conditional Expression 12, f is the total focal length of the optical system, f5 is the focal length of the fifth lens, and f6 is the focal length of the sixth lens.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 13.

[Conditional Expression 13]

1.5 <TTL/ImgH <1.7

In Conditional Expression 13, TTL is the distance from the object side surface of the first lens to the image sensor, and ImgH is half the diagonal length of the image sensor.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 14.

[Conditional Expression 14]

65 <FOV <80

In Conditional Equation 14, the FOV is the angle of view of the optical system. Here, the unit of the angle of view of the optical system is degrees.

The optical system according to an embodiment of the present invention satisfies Conditional Expression 15.

[Conditional Expression 15]

SA2 ≤ 30

In Conditional Equation 15, SA2 is an angle between the tangent line at the end of the effective mirror of the image-side surface of the second lens and the image sensor (see FIG. 17). Here, the unit of the angle is Degree.

Next, the first to sixth lenses constituting the optical system according to an exemplary embodiment of the present invention will be described.

The first lens has positive refractive power. In addition, the first lens may have a convex shape on both sides. To further explain, the first surface of the first lens is convex toward the object in the paraxial region, and the second surface of the first lens is convex toward the image in the paraxial region.

In addition, the first lens may have a meniscus shape that is convex toward the object side. To further explain, the first and second surfaces of the first lens may have a convex shape toward the object in the paraxial region.

At least one of the first and second surfaces of the first lens may be an aspherical surface. For example, both surfaces of the first lens may be aspherical.

The second lens has negative refractive power. In addition, the second lens has a meniscus shape convex toward the object side. To further explain, the first and second surfaces of the second lens may have a convex shape toward the object in the paraxial region.

At least one of the first and second surfaces of the second lens may be an aspherical surface. For example, both surfaces of the second lens may be aspherical.

The third lens has positive refractive power. In addition, the third lens may have a meniscus shape that is convex toward the image side. To further explain, the first and second surfaces of the third lens may be convex upward in the paraxial region.

In addition, the third lens may have a convex shape on both sides. To further explain, the first surface of the third lens is convex toward the object in the paraxial region, and the second surface of the third lens is convex toward the image in the paraxial region.

At least one of the first and second surfaces of the third lens may be an aspherical surface. For example, both surfaces of the third lens may be aspherical.

The fourth lens has positive or negative refractive power. In addition, the fourth lens has a meniscus shape that is convex toward the image side. To further explain, the first and second surfaces of the fourth lens may be convex upward in the paraxial region.

At least one of the first and second surfaces of the fourth lens may be an aspherical surface. For example, both surfaces of the fourth lens may be aspherical.

The fifth lens has negative refractive power. In addition, the fifth lens may have a concave shape on both sides. To further explain, the first surface of the fifth lens may be concave toward the object in the paraxial region, and the second surface of the fifth lens may be concave toward the image in the paraxial region.

In addition, the fifth lens may have a meniscus shape that is convex toward the object side. To further explain, the first and second surfaces of the fifth lens may have a convex shape toward the object in the paraxial region.

At least one of the first and second surfaces of the fifth lens may be an aspherical surface. For example, both surfaces of the fifth lens may be aspherical.

In addition, at least one inflection point is formed on at least one of the first and second surfaces of the fifth lens. For example, the second surface of the fifth lens may be concave in the paraxial region and convex toward the edge.

The sixth lens has positive refractive power. In addition, the sixth lens may have a meniscus shape that is convex toward the object side. To further explain, the first and second surfaces of the sixth lens may have a convex shape toward the object in the paraxial region.

At least one of the first and second surfaces of the sixth lens may be an aspherical surface. For example, both surfaces of the sixth lens may be aspherical.

In addition, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens. For example, the second surface of the sixth lens may be concave in the paraxial region and convex toward the edge.

The optical system configured as described above can improve aberration improvement performance because a plurality of lenses perform an aberration correction function.

An optical system according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

The optical system according to the first embodiment of the present invention includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, and a sixth lens. An optical system including 160 may be included, and a stop, an infrared cut filter 170, and an image sensor 180 may be further included.

As shown in Table 1, the focal length f1 of the first lens 110 is 2.85 mm, the focal length f2 of the second lens 120 is -5.3 mm, and The focal length f3 is 28.86 mm, the focal length f4 of the fourth lens 140 is 741.25 mm, the focal length f5 of the fifth lens 150 is -12.35 mm, and the sixth lens 160 is The focal length f6 of) is 32.76 mm, and the total focal length f of the optical system is 4.16 mm.

Here, the lens characteristics (radius of curvature, thickness of the lens or distance between lenses (Thickness), refractive index, and Abbe number) of each lens are as shown in FIG. 3.

In the first embodiment of the present invention, the first lens 110 has positive refractive power and has a convex shape on both sides. For example, the first surface of the first lens 110 is convex toward the object in the paraxial region, and the second surface of the first lens 110 is convex toward the image in the paraxial region.

The second lens 120 has negative refractive power and has a meniscus shape that is convex toward the object side. For example, the first and second surfaces of the second lens 120 are convex toward the object in the paraxial region.

The third lens 130 has positive refractive power and has a meniscus shape that is convex toward the image. For example, the first and second surfaces of the third lens 130 are convex upward in the paraxial region.

The fourth lens 140 has positive refractive power and has a meniscus shape that is convex toward the image side. For example, the first and second surfaces of the fourth lens 140 are convex upward in the paraxial region.

The fifth lens 150 has negative refractive power, and both surfaces thereof are concave. For example, the first surface of the fifth lens 150 is concave toward the object in the paraxial region, and the second surface of the fifth lens 150 is concave toward the image in the paraxial region. In addition, at least one inflection point is formed on at least one of the first and second surfaces of the fifth lens 150.

The sixth lens 160 has positive refractive power and has a meniscus shape that is convex toward the object side. For example, the first and second surfaces of the sixth lens 160 are convex toward the object in the paraxial region. In addition, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens 160.

Meanwhile, each surface of the first to sixth lenses 110 to 160 has an aspherical surface coefficient as shown in FIG. 4.

In addition, the stop may be disposed in front of the object-side surface of the first lens 110.

In addition, the optical system configured as described above may have aberration characteristics illustrated in FIG. 2.

An optical system according to a second embodiment of the present invention will be described with reference to FIGS. 5 to 8.

The optical system according to the second embodiment of the present invention includes a first lens 210, a second lens 220, a third lens 230, a fourth lens 240, a fifth lens 250, and a sixth lens. An optical system having 260 may be included, and a stop, an infrared cut filter 270 and an image sensor 280 may be further included.

As shown in Table 2, the focal length f1 of the first lens 210 is 3.42 mm, the focal length f2 of the second lens 220 is -7.24 mm, and The focal length f3 is 33.42 mm, the focal length f4 of the fourth lens 240 is 64.65 mm, the focal length f5 of the fifth lens 250 is -12.94 mm, and the sixth lens 260 is -12.94 mm. The focal length f6 of) is 1380 mm, and the total focal length f of the optical system is 4.71 mm.

Here, the lens characteristics (radius of curvature (radius), thickness of the lens or distance between lenses (Thickness), refractive index (Index), Abbe number) of each lens) are as shown in FIG. 7.

In the second embodiment of the present invention, the first lens 210 has a positive refractive power and has a meniscus shape that is convex toward an object side. For example, the first and second surfaces of the first lens 210 may be convex toward the object in the paraxial region.

The second lens 220 has negative refractive power and has a meniscus shape that is convex toward an object. For example, the first and second surfaces of the second lens 220 may be convex toward the object in the paraxial region.

The third lens 230 has positive refractive power and has a convex shape on both sides. For example, a first surface of the third lens 230 may be convex toward an object in a paraxial region, and a second surface of the third lens 230 may be convex toward an image in a paraxial region.

The fourth lens 240 has positive refractive power and has a meniscus shape that is convex toward the image. For example, the first and second surfaces of the fourth lens 240 may be convex upward in the paraxial region.

The fifth lens 250 has negative refractive power and has a meniscus shape convex toward the object side. For example, the first and second surfaces of the fifth lens 250 may be convex toward the object in the paraxial region. In addition, at least one inflection point is formed on at least one of the first and second surfaces of the fifth lens 250.

The sixth lens 260 has negative refractive power and has a meniscus shape that is convex toward the object side. For example, the first and second surfaces of the sixth lens 260 may be convex toward the object in the paraxial region. In addition, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens 260.

Meanwhile, each surface of the first to sixth lenses 210 to 260 has an aspherical surface coefficient as illustrated in FIG. 8.

In addition, the aperture may be disposed in front of the object-side surface of the first lens 210.

In addition, the optical system configured as described above may have aberration characteristics illustrated in FIG. 6.

An optical system according to a third embodiment of the present invention will be described with reference to FIGS. 9 to 12.

The optical system according to the third embodiment of the present invention includes a first lens 310, a second lens 320, a third lens 330, a fourth lens 340, a fifth lens 350, and a sixth lens. An optical system having 360 may be included, and a stop, an infrared cut filter 370 and an image sensor 380 may be further included.

As shown in Table 3, the focal length f1 of the first lens 310 is 3.16 mm, the focal length f2 of the second lens 320 is -5.71 mm, and The focal length f3 is 19.16 mm, the focal length f4 of the fourth lens 340 is 39 mm, the focal length f5 of the fifth lens 350 is -15 mm, and the sixth lens 360 The focal length f6 of) is 84 mm, and the total focal length f of the optical system is 4.2 mm.

Here, the lens characteristics (radius of curvature (radius), thickness of the lens, or distance between lenses (Thickness), refractive index (Index), Abbe number) of each lens are as shown in FIG. 11.

In the third embodiment of the present invention, the first lens 310 has positive refractive power and has a convex shape on both sides. For example, the first surface of the first lens 310 is convex toward the object in the paraxial region, and the second surface of the first lens 310 is convex toward the image in the paraxial region.

The second lens 320 has negative refractive power and has a meniscus shape that is convex toward the object side. For example, the first and second surfaces of the second lens 320 are convex toward the object in the paraxial region.

The third lens 130 has positive refractive power and has a convex shape on both sides. For example, the first surface of the third lens 330 is convex toward the object in the paraxial region, and the second surface of the third lens 330 is convex toward the image in the paraxial region.

The fourth lens 340 has positive refractive power and has a meniscus shape that is convex toward the image side. For example, the first and second surfaces of the fourth lens 340 are convex upward in the paraxial region.

The fifth lens 350 has negative refractive power, and both surfaces are concave. For example, the first surface of the fifth lens 350 is concave toward the object in the paraxial region, and the second surface of the fifth lens 350 is concave toward the image in the paraxial region. In addition, at least one inflection point is formed on at least one of the first and second surfaces of the fifth lens 350.

The sixth lens 360 has positive refractive power and has a meniscus shape that is convex toward the object side. For example, the first and second surfaces of the sixth lens 360 are convex toward the object in the paraxial region. In addition, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens 360.

Meanwhile, each surface of the first to sixth lenses 310 to 360 has an aspherical surface coefficient as illustrated in FIG. 12.

In addition, the stop may be disposed in front of the object-side surface of the first lens 310.

In addition, the optical system configured as described above may have aberration characteristics illustrated in FIG. 10.

An optical system according to a fourth exemplary embodiment of the present invention will be described with reference to FIGS. 13 to 16.

The optical system according to the fourth embodiment of the present invention includes a first lens 410, a second lens 420, a third lens 430, a fourth lens 440, a fifth lens 450, and a sixth lens. An optical system having 460 may be included, and a stop, an infrared cut filter 470, and an image sensor 480 may be further included.

As shown in Table 4, a focal length f1 of the first lens 410 is 2.88 mm, a focal length f2 of the second lens 420 is -4.95 mm, and The focal length f3 is 20.7 mm, the focal length f4 of the fourth lens 440 is -74.3 mm, the focal length f5 of the fifth lens 450 is -12.4 mm, and the sixth lens ( The focal length f6 of 460 is 25.66 mm, and the total focal length f of the optical system is 4.4 mm.

Here, the lens characteristics (radius of curvature (radius), thickness of the lens, or distance between lenses (Thickness), refractive index (Index), Abbe number) of each lens are as shown in FIG. 15.

In the fourth embodiment of the present invention, the first lens 410 has positive refractive power and has a convex shape on both sides. For example, a first surface of the first lens 410 is convex toward an object in a paraxial region, and a second surface of the first lens 410 is convex toward an image in a paraxial region.

The second lens 420 has negative refractive power and has a meniscus shape that is convex toward the object side. For example, the first and second surfaces of the second lens 420 are convex toward the object in the paraxial region.

The third lens 430 has positive refractive power and has a meniscus shape that is convex toward the image. For example, the first and second surfaces of the third lens 430 are convex upward in the paraxial region.

The fourth lens 440 has negative refractive power and has a meniscus shape that is convex toward the image side. For example, the first and second surfaces of the fourth lens 440 are convex upward in the paraxial region.

The fifth lens 450 has negative refractive power, and both surfaces thereof are concave. For example, the first surface of the fifth lens 450 is concave toward the object in the paraxial region, and the second surface of the fifth lens 450 is concave toward the image in the paraxial region. In addition, at least one inflection point is formed on at least one of the first and second surfaces of the fifth lens 450.

The sixth lens 460 has positive refractive power and has a meniscus shape that is convex toward the object side. For example, the first and second surfaces of the sixth lens 460 are convex toward the object in the paraxial region. In addition, at least one inflection point is formed on at least one of the first and second surfaces of the sixth lens 460.

Meanwhile, each surface of the first to sixth lenses 410 to 460 has an aspherical surface coefficient as shown in FIG. 16.

In addition, the stop may be disposed in front of the object-side surface of the first lens 410.

In addition, the optical system configured as described above may have aberration characteristics illustrated in FIG. 14.

In the above, the configuration and features of the present invention have been described based on the embodiments according to the present invention, but the present invention is not limited thereto, and it is understood that various changes or modifications can be made within the spirit and scope of the present invention. It will be apparent to those skilled in the art, and therefore, such changes or modifications are found to belong to the appended claims.

110, 210, 310, 410: first lens
120, 220, 320, 420: second lens
130, 230, 330, 430: third lens
140, 240, 340, 440: fourth lens
150, 250, 350, 450: fifth lens
160, 260, 360, 460: sixth lens
170, 270, 370, 470: infrared cut filter
180, 280, 380, 480: image sensor
Stop: aperture

Claims (13)

In order from the object side,
A first lens having positive refractive power and having a convex object-side surface;
A second lens having negative refractive power, a convex object-side surface and a concave image-side surface;
A third lens having positive refractive power and having a convex image-side surface;
A fourth lens having refractive power;
A fifth lens having refractive power; And
Includes; a sixth lens having refractive power,
When the distance from the object-side surface of the first lens to the image pickup surface is TTL, 1.1 <TTL/f <1.35 is satisfied,
When the Abbe number of the first lens is v1 and the Abbe number of the second lens is v2,
An imaging optical system that satisfies v1-v2> 20.
The method of claim 1,
The first lens is an optical system having a concave image-side surface.
The method of claim 1,
The third lens is an optical system in which an object-side surface is convex.
The method of claim 1,
The fourth lens has negative refractive power, and an object-side surface is concave and an image-side surface is convex.
The method of claim 1,
The fifth lens is an optical system in which an object-side surface is convex and an image-side surface is concave.
The method of claim 1,
The sixth lens is an optical system in which an object-side surface is convex and an image-side surface is concave.
The method of claim 1,
When the angle of view of the imaging optical system is the FOV,
Imaging optical system that satisfies 65° <FOV <80°.
The method of claim 1,
When the focal length of the fifth lens is f5, and the total focal length of the optical system including the first to sixth lenses is f,
0.2 <|f/f5| An imaging optical system satisfying <0.4.
The method of claim 8,
When the focal length of the sixth lens is f6,
0.3 <|f/f5| + |f/f6| An imaging optical system satisfying <0.6.
The method of claim 1,
When the distance from the object-side surface of the first lens to the imaging surface is TTL, and half of the diagonal length of the imaging surface is ImgH,
An imaging optical system that satisfies 1.5 <TTL/ImgH <1.7.
The method of claim 1,
All of the first to sixth lenses are made of plastic.
The method of claim 11,
Each of the first to sixth lenses has an object-side surface and an image-side surface of each aspherical surface.
The method of claim 12,
At least one of an object-side surface and an image-side surface of the sixth lens has at least one inflection point.

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