Optical imaging system

Abstract

The present invention provides an optical imaging system, the optical imaging system comprising: a first lens having a negative refractive power; a second lens having a negative refractive power; a third lens; a fourth lens; a fifth lens; a sixth lens; and a seventh lens. The first lens to the seventh lens are sequentially arranged from the object side towards the image side. The third lens and the seventh lens are formed of plastic, and the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens are formed of glass.

Description

[0001] This application claims the priority and benefit of Korean Patent Application No. 10-2017-0155623, filed with the Korean Intellectual Property Office on November 21, 2017, the entire disclosure of which is incorporated herein by reference for all purposes. Technical Field

[0002] This application relates to an optical imaging system. Background Art

[0003] Generally, a camera module is mounted in a mobile communication terminal, a computer, a vehicle, etc., and is capable of capturing an image.

[0004] According to the trend of thinner mobile communication terminals, there has been a need for such a camera module to have a small size and high image quality.

[0005] Meanwhile, a camera module for a vehicle has also been required to have a small size and high image quality so as not to obstruct the driver's view and not to damage the appearance of the vehicle.

[0006] In particular, a camera used in a rearview mirror of a vehicle should be able to capture a clear image to ensure a rear view during driving of the vehicle, and thus needs to have high image quality.

[0007] In addition, even when the illuminance is low at night, a camera used in a vehicle should be able to clearly capture an image of an object, and thus needs a lens system that has a small size and can capture images in both the visible light wavelength region and the near-infrared region.

[0008] The above information is presented only as background information to aid in understanding the present disclosure. No determination has been made as to whether any of the above is applicable as prior art with respect to the present disclosure, and no assertion is made. Summary of the Invention

[0009] In one general aspect, an optical imaging system includes: a first lens having a negative refractive power; a second lens having a negative refractive power; a third lens; a fourth lens; a fifth lens; a sixth lens; and a seventh lens. The first lens to the seventh lens are sequentially arranged from the object side toward the image side, the third lens and the seventh lens are formed of plastic, and the first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens are formed of glass.

[0010] The object-side surface and the image-side surface of the first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens may be spherical surfaces, and the object-side surface and the image-side surface of the third lens and the seventh lens may be aspherical surfaces.

[0011] The third lens and the seventh lens can be formed of plastics having the same optical properties as each other.

[0012] The fifth lens and the sixth lens can be formed of glasses having different optical properties from each other.

[0013] The fifth lens and the sixth lens can be cemented to each other.

[0014] The optical imaging system may further include a diaphragm disposed between the fourth lens and the fifth lens.

[0015] In the optical imaging system, TTL is the distance from the object surface of the first lens to the imaging surface of the image sensor, IMGH is half of the diagonal length of the imaging surface of the image sensor, and TTL / (2×IMGH) can be less than 3.05.

[0016] In the optical imaging system, R5 is the radius of curvature of the object surface of the third lens, f is the total focal length of the optical imaging system including the first lens to the seventh lens, and R5 / f can be greater than -15.0 and less than -5.0.

[0017] In the optical imaging system, f3 is the focal length of the third lens, and f / f3 can be greater than 0.02 and less than 0.08.

[0018] In the optical imaging system, f7 is the focal length of the seventh lens, and f / f7 can be greater than 0.4 and less than 0.48.

[0019] In the optical imaging system, n3 is the refractive index of the third lens, and n3 can be less than 1.535.

[0020] In the optical imaging system, n7 is the refractive index of the seventh lens, and n7 can be less than 1.535.

[0021] In the optical imaging system, R1 is the radius of curvature of the object surface of the first lens, R2 is the radius of curvature of the image surface of the first lens, and R1 / R2 can be greater than 3.5.

[0022] In the optical imaging system, R3 is the radius of curvature of the object surface of the second lens, R4 is the radius of curvature of the image surface of the second lens, and R3 / R4 can be greater than 10.

[0023] In another general aspect, an optical imaging system includes: a first lens having a negative refractive power and a meniscus shape with its object-side surface being convex; a second lens having a negative refractive power and a meniscus shape with its object-side surface being convex; a third lens; a fourth lens; a fifth lens; a sixth lens; and a seventh lens. The first lens to the seventh lens are arranged in sequence from the object side toward the image side. The third lens and the seventh lens are formed of plastic. The first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens are formed of glass, and the image-side surface of the fifth lens and the object-side surface of the sixth lens are cemented to each other.

[0024] Both the third lens and the seventh lens may have a positive refractive power.

[0025] The third lens may have a concave object-side surface and a convex image-side surface, and both the fourth lens and the seventh lens may have a convex object-side surface and a convex image-side surface.

[0026] Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. Description of the Drawings

[0027] Figure 1 is a diagram showing a first example of the optical imaging system.

[0028] Figure 2 shows an example of Figure 1 a curve representing the aberration characteristics of the optical imaging system shown in

[0029] Figure 3 is a diagram showing a second example of the optical imaging system.

[0030] Figure 4 shows an example of Figure 3 a curve representing the aberration characteristics of the optical imaging system shown in

[0031] In all the drawings and the detailed description, the same reference numerals indicate the same elements. The drawings may not be drawn to scale, and for clarity, illustration, and convenience, the relative dimensions, proportions, and depictions of the elements in the drawings may be exaggerated. Detailed Description

[0032] The following specific embodiments are provided to assist the reader in obtaining a comprehensive understanding of the methods, devices, and / or systems described herein. However, after understanding the disclosure of the present application, various variations, modifications, and equivalents of the methods, devices, and / or systems described herein will be apparent. For example, the order of operations described herein is merely exemplary and is not limited to the order set forth herein, but rather variations that will be apparent after understanding the disclosure of the present application may be made, except for operations that must occur in a specific order. In addition, descriptions of features known in the art may be omitted for the sake of clarity and conciseness.

[0033] The features described herein may be implemented in different forms and will not be construed as being limited by the examples described herein. Rather, the examples described herein have been provided only to illustrate some of the many possible ways of implementing the methods, devices, and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0034] In the drawings, for the sake of explanation, the thickness, dimensions, and shape of the lens have been slightly exaggerated. In particular, the shapes of the spherical surfaces or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical surfaces or aspherical surfaces are not limited to the shapes shown in the drawings.

[0035] In the present application, the first lens refers to the lens closest to the object, and the seventh lens refers to the lens closest to the image sensor.

[0036] In addition, the first surface of each lens refers to the surface closest to the object side (or object-side surface), and the second surface of each lens refers to the surface closest to the image side (or image-side surface). Furthermore, all numerical values such as the radius of curvature and thickness of the lens, the image height (IMGH, half of the diagonal length of the imaging surface of the image sensor), etc. are expressed in millimeters (mm), and the field of view (FOV) of the optical imaging system is expressed in degrees.

[0037] In addition, in the description of the shape of each of the lenses, the meaning that a surface of the lens is convex is that the paraxial region portion of the corresponding surface is convex, and the meaning that a surface of the lens is concave is that the paraxial region portion of the corresponding surface is concave. Thus, although a surface of the lens is described as being convex, the edge portion of the said surface of the lens may be concave. Similarly, although a surface of the lens is described as being concave, the edge portion of the said surface of the lens may be convex.

[0038] The paraxial region refers to a very narrow region near the optical axis.

[0039] One aspect of the present disclosure provides an optical imaging system, in which the aberration improvement effect can be enhanced, a high level of resolution can be achieved, imaging can be performed even in an environment with low illuminance, and deviation of resolution can be suppressed even under a wide range of temperature variations.

[0040] The optical imaging system in the example described herein may include seven lenses.

[0041] For example, the optical imaging system may include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens sequentially arranged from the object side.

[0042] However, the optical imaging system is not limited to including only seven lenses, but may also include other components if necessary.

[0043] For example, the optical imaging system may further include an image sensor configured to convert an image of a subject incident on the image sensor into an electrical signal. The image sensor may be configured to capture an image of an object in the near-infrared region as well as the visible light region.

[0044] In addition, the optical imaging system may further include a diaphragm configured to control the amount of light. For example, the diaphragm may be disposed between the fourth lens and the fifth lens.

[0045] In the optical imaging system in the example described herein, some of the first lens to the seventh lens may be formed of plastic, and the other lenses of the first lens to the seventh lens may be formed of glass. In addition, the lenses formed of glass may have optical properties different from those of the lenses formed of plastic.

[0046] For example, the first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens may be formed of glass, and the third lens and the seventh lens may be formed of plastic.

[0047] In addition, in the optical imaging system in the example described herein, some of the first lens to the seventh lens may be aspherical lenses, and the other lenses of the first lens to the seventh lens may be spherical lenses.

[0048] As an example, the first surface and the second surface of the first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens may be spherical surfaces, and the first surface and the second surface of the third lens and the seventh lens may be aspherical surfaces.

[0049] The aspherical surfaces of the third lens and the seventh lens may be represented by Equation 1 below:

[0050]

[0051] In Equation 1, c is the curvature of the lens (the reciprocal of the radius of curvature), K is the conic constant, and Y is the distance from a point on the aspherical surface of the lens to the optical axis in a direction perpendicular to the optical axis. Additionally, constant A to constant D are aspherical coefficients. Further, Z is the distance between a point on the aspherical surface of the lens at a distance Y from the optical axis and the tangent plane tangent to the vertex of the aspherical surface of the lens.

[0052] The optical imaging system including the first lens to the seventh lens may sequentially have a negative refractive power, a negative refractive power, a positive refractive power, a positive refractive power, a positive refractive power, a negative refractive power, and a positive refractive power from the object side.

[0053] The optical imaging system in the examples described herein may satisfy the following conditional expressions 2 to conditional expression 9:

[0054] TTL / (2×IMGH)<3.05 (2)

[0055] -15.0<R5 / f<-5.0 (3)

[0056] 0.02<f / f3<0.08 (4)

[0057] 0.4<f / f7<0.48 (5)

[0058] n3<1.535 (6)

[0059] n7<1.535 (7)

[0060] R1 / R2>3.5 (8)

[0061] R3 / R4>10 (9)

[0062] In the above conditional expressions 2 to conditional expression 9, TTL is the distance from the object-side surface of the first lens to the imaging surface of the image sensor, IMGH is half of the diagonal length of the imaging surface of the image sensor, R5 is the radius of curvature of the object-side surface of the third lens, f is the total focal length of the optical imaging system, f3 is the focal length of the third lens, f7 is the focal length of the seventh lens, n3 is the refractive index of the third lens, n7 is the refractive index of the seventh lens, R1 is the radius of curvature of the object-side surface of the first lens, R2 is the radius of curvature of the image-side surface of the first lens, R3 is the radius of curvature of the object-side surface of the second lens, and R4 is the radius of curvature of the image-side surface of the second lens.

[0063] Next, the first lens to the seventh lens constituting the optical imaging system in some examples will be described.

[0064] The first lens may have a negative refractive power. Additionally, the first lens may have a meniscus shape with its object-side surface being convex. Specifically, the first surface of the first lens may be convex in the paraxial region, and its second surface may be concave in the paraxial region.

[0065] The two surfaces of the first lens may be spherical surfaces.

[0066] The second lens may have a negative refractive power. Additionally, the second lens may have a meniscus shape with its object-side surface being convex. Specifically, the first surface of the second lens may be convex in the paraxial region, and its second surface may be concave in the paraxial region.

[0067] The two surfaces of the second lens may be spherical surfaces.

[0068] The third lens may have a positive refractive power. Additionally, the third lens may have a meniscus shape with its image-side surface being convex. Specifically, the first surface of the third lens may be concave in the paraxial region, and its second surface may be convex in the paraxial region.

[0069] The two surfaces of the third lens may be aspherical surfaces.

[0070] The fourth lens may have a positive refractive power. Additionally, the two surfaces of the fourth lens may be convex. Specifically, the first surface and the second surface of the fourth lens may be convex in the paraxial region.

[0071] The two surfaces of the fourth lens may be spherical surfaces.

[0072] The fifth lens may have a positive refractive power. Additionally, the two surfaces of the fifth lens may be convex. Specifically, the first surface and the second surface of the fifth lens may be convex in the paraxial region.

[0073] The two surfaces of the fifth lens may be spherical surfaces.

[0074] The sixth lens may have a negative refractive power. Additionally, the two surfaces of the sixth lens may be concave. Specifically, the first surface and the second surface of the sixth lens may be concave in the paraxial region.

[0075] The two surfaces of the sixth lens may be spherical surfaces.

[0076] Meanwhile, the fifth lens and the sixth lens may be configured as a cemented lens. As an example, the image-side surface of the fifth lens and the object-side surface of the sixth lens may be cemented to each other.

[0077] The seventh lens may have a positive refractive power. Additionally, the two surfaces of the seventh lens may be convex. Specifically, the first surface and the second surface of the seventh lens may be convex in the paraxial region.

[0078] The two surfaces of the seventh lens may be aspherical surfaces.

[0079] In the optical imaging system configured as described above, a plurality of lenses can perform an aberration correction function, thereby improving the aberration improvement performance.

[0080] In addition, the optical imaging system may have an f-number (Fno) of 2.4 or less (a constant indicating the brightness of the optical imaging system), so that an image of an object can be clearly captured even in an environment with low illuminance.

[0081] In addition, the optical imaging system can clearly capture an image of an object in both the visible light region and the near-infrared region.

[0082] In addition, in the optical imaging system in some of the examples described herein, the first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens can be configured as spherical lenses, thereby reducing the cost of manufacturing the optical imaging system.

[0083] In addition, in the optical imaging system in some of the examples described herein, since the first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens are formed of glass having a relatively small coefficient of thermal expansion, and the third lens and the seventh lens are formed of plastic, a constant resolution can be maintained even in a temperature range of about -40°C to about 80°C. Therefore, even in an environment where the temperature varies over a wide range, the optical imaging system in some of the examples described herein can achieve a high level of resolution.

[0084] The housing in which the first lens to the seventh lens are disposed can be formed of plastic, and the housing can contract or expand according to the temperature change of the surrounding environment. Therefore, the distance between the seventh lens and the image sensor can change due to the deformation of the housing according to the temperature change, which may cause a problem that the focus cannot be correctly converged.

[0085] However, in the optical imaging system in some of the examples described herein, since the third lens and the seventh lens are formed of plastic, the third lens and the seventh lens can contract or expand according to the temperature change of the surrounding environment.

[0086] Therefore, by designing the deformation amounts of the third lens and the seventh lens in consideration of the amount of shape deformation of the housing according to the temperature change, the focus position does not change even in the case of temperature change.

[0087] That is, the optical imaging system in some of the examples described herein can be configured such that the change in the distance between the seventh lens and the image sensor according to the temperature change corresponds to the change in the focus position according to the temperature change.

[0088] Will be referred to Figure 1 and Figure 2Describe the optical imaging system according to the first example disclosed herein.

[0089] The optical imaging system according to the first example may include an optical system, which includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160, and a seventh lens 170, and may also include a diaphragm ST, a filter 180, and an image sensor 190.

[0090] Table 1 shows the lens characteristics (radius of curvature, lens thickness or distance between lenses, refractive index, and Abbe number) of each lens.

[0091] Table 1

[0092]

[0093] In the surface numbers of Table 1, the symbol * indicates an aspherical surface.

[0094] In the first example, the first lens 110 may have a negative refractive power, and its first surface may be convex in the paraxial region, and its second surface may be concave in the paraxial region.

[0095] The second lens 120 may have a negative refractive power, and its first surface may be convex in the paraxial region, and its second surface may be concave in the paraxial region.

[0096] The third lens 130 may have a positive refractive power, and its first surface may be concave in the paraxial region, and its second surface may be convex in the paraxial region.

[0097] The fourth lens 140 may have a positive refractive power, and its first surface and second surface may be convex in the paraxial region.

[0098] The fifth lens 150 may have a positive refractive power, and its first surface and second surface may be convex in the paraxial region.

[0099] The sixth lens 160 may have a negative refractive power, and its first surface and second surface may be concave in the paraxial region.

[0100] The seventh lens 170 may have a positive refractive power, and its first surface and second surface may be convex in the paraxial region.

[0101] Meanwhile, the corresponding surfaces of the third lens 130 and the seventh lens 170 may have the aspherical coefficients shown in Table 2.

[0102] Table 2

[0103] Surface number K A B C D 5 -0.01028 -0.00475 0.000166 -9.8E-05 1.12E-05 6 -0.18758 -0.00073 0.000548 -0.00011 2.4E-05 13 -0.78800 -0.00539 0.000305 -1.3E-05 2.65E-07 14 -5.95155 -0.00404 0.00019 -9.1E-06 6.75E-08

[0104] In addition, the first lens 110, the second lens 120, the fourth lens 140, the fifth lens 150, and the sixth lens 160 may be spherical lenses and may be formed of glass. The third lens 130 and the seventh lens 170 may be aspherical lenses and may be formed of plastic.

[0105] In addition, the third lens 130 and the seventh lens 170 may be formed of plastic having the same optical properties as each other.

[0106] Meanwhile, the fifth lens 150 and the sixth lens 160 may be configured as a cemented lens. That is, the fifth lens 150 and the sixth lens 160 may be cemented (bonded) to each other. For example, the image-side surface of the fifth lens 150 may be cemented to the object-side surface of the sixth lens 160. The fifth lens 150 and the sixth lens 160 may be formed of glass having different optical properties from each other.

[0107] The fifth lens 150 and the sixth lens 160 formed of glass having different optical properties may be configured as a cemented lens, thereby improving the chromatic aberration correction performance.

[0108] In addition, the aperture stop ST may be disposed in front of the cemented lens. As an example, the aperture stop ST may be disposed between the fourth lens 140 and the fifth lens 150.

[0109] In addition, the optical imaging system configured as described above may have Figure 2 the aberration characteristics shown in

[0110] Reference will be made to Figure 3 and Figure 4 to describe the optical imaging system according to the second example disclosed herein.

[0111] The optical imaging system according to the second example may include an optical system including a first lens 210, a second lens 220, a third lens 230, a fourth lens 240, a fifth lens 250, a sixth lens 260, and a seventh lens 270, and may further include an aperture stop ST, a filter 280, and an image sensor 290.

[0112] Table 3 shows the lens characteristics (radius of curvature, lens thickness or distance between lenses, refractive index, and Abbe number) of each lens.

[0113] Table 3

[0114]

[0115] In the surface numbers in Table 3, the symbol * indicates an aspherical surface.

[0116] In a second example, the first lens 210 may have a negative refractive power, and its first surface may be convex in the paraxial region, and its second surface may be concave in the paraxial region.

[0117] The second lens 220 may have a negative refractive power, and its first surface may be convex in the paraxial region, and its second surface may be concave in the paraxial region.

[0118] The third lens 230 may have a positive refractive power, and its first surface may be concave in the paraxial region, and its second surface may be convex in the paraxial region.

[0119] The fourth lens 240 may have a positive refractive power, and its first surface and second surface may be convex in the paraxial region.

[0120] The fifth lens 250 may have a positive refractive power, and its first surface and second surface may be convex in the paraxial region.

[0121] The sixth lens 260 may have a negative refractive power, and its first surface and second surface may be concave in the paraxial region.

[0122] The seventh lens 270 may have a positive refractive power, and its first surface and second surface may be convex in the paraxial region.

[0123] Meanwhile, the respective first surfaces and second surfaces of the third lens 230 and the seventh lens 270 may have aspherical coefficients as shown in Table 4.

[0124] Table 4

[0125] Surface number K A B C D 5 94.32793 -0.00277 0.000518 -0.00021 3.60E-05 6 6.676489 0.000536 0.000343 -6.72E-05 1.84E-05 13 -1.34768 -0.00615 0.000573 -9.07E-05 6.00E-06 14 -14.2459 -0.00876 0.000907 -8.55E-05 2.68E-06

[0126] In addition, the first lens 210, the second lens 220, the fourth lens 240, the fifth lens 250, and the sixth lens 260 may be spherical lenses and may be formed of glass. The third lens 230 and the seventh lens 270 may be aspherical lenses and may be formed of plastic.

[0127] In addition, the third lens 230 and the seventh lens 270 may be formed of plastic having the same optical properties as each other.

[0128] Meanwhile, the fifth lens 250 and the sixth lens 260 may be configured as cemented lenses. The fifth lens 250 and the sixth lens 260 may be formed of glass having different optical properties from each other.

[0129] The fifth lens 250 and the sixth lens 260 formed of glass having different optical properties from each other may be configured as cemented lenses, thereby improving the chromatic aberration correction performance.

[0130] In addition, the aperture ST can be disposed in front of the cemented lens. As an example, the aperture ST can be disposed between the fourth lens 240 and the fifth lens 250.

[0131] In addition, the optical imaging system configured as described above can have Figure 4 the aberration characteristics shown in

[0132] As described above, in the optical imaging system in the examples disclosed herein, the aberration improvement effect can be enhanced, a high level of resolution can be achieved, imaging can be performed even in an environment with low illuminance, and deviation of resolution can be suppressed even under a wide range of temperature variations.

[0133] Although the present disclosure includes specific examples, it will be apparent after understanding the disclosure of the present application that various changes in form and detail can be made to these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be understood in a descriptive sense only and not for purposes of limitation. The description of a feature or aspect in each example is to be understood as applicable to similar features or aspects in other examples. Suitable results can be obtained if the described techniques are performed in a different order, and / or if the described components of the system, architecture, device, or circuit are combined in a different form and / or replaced or augmented by other components or their equivalents. Accordingly, the scope of the present disclosure is defined not by the specific embodiments but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be understood as being included in the present disclosure.

Claims

1. An ultra-wide-angle optical imaging system, the optical imaging system comprising: A first lens having a negative refractive power and a concave image-side surface; A second lens having a negative refractive power and a concave image-side surface; A third lens having a positive refractive power; A fourth lens having a positive refractive power and a convex image-side surface; A fifth lens having a positive refractive power and a convex object-side surface; A sixth lens having a negative refractive power, a concave object-side surface and a concave image-side surface; And A seventh lens having a positive refractive power, a convex object-side surface and a convex image-side surface, Wherein, the optical imaging system includes a total of seven lenses with refractive power, and the first lens to the seventh lens are sequentially arranged from the object side towards the image side, Wherein, the third lens and the seventh lens are formed of plastics having the same optical properties as each other, and both the third lens and the seventh lens have a refractive index less than 1.535, Wherein, the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens are formed of glass, where TTL is the distance from the object side surface of the first lens to the imaging surface of the image sensor, IMGH is half of the diagonal length of the imaging surface of the image sensor, and <TTL / (2 IMGH)< .

2. The optical imaging system according to claim 1, wherein, The object-side surface and the image-side surface of the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens are spherical surfaces, and the object-side surface and the image-side surface of the third lens and the seventh lens are aspherical surfaces.

3. The optical imaging system according to claim 1, wherein, The fifth lens and the sixth lens are formed of glasses having different optical properties from each other.

4. The optical imaging system according to claim 3, wherein, The fifth lens and the sixth lens are cemented to each other.

5. The optical imaging system according to claim 1, the optical imaging system further comprising a diaphragm disposed between the fourth lens and the fifth lens.

6. The optical imaging system according to claim 1, wherein, R5 is the radius of curvature of the object-side surface of the third lens, f is the total focal length of the optical imaging system including the first lens to the seventh lens, and < R5 / f < .

7. The optical imaging system according to claim 1, wherein f3 is the focal length of the third lens, f is the total focal length of the optical imaging system including the first lens to the seventh lens, and < f / f3 < .

8. The optical imaging system according to claim 1, wherein, f7 is the focal length of the seventh lens, f is the total focal length of the optical imaging system including the first lens to the seventh lens, and < f / f7 < .

9. The optical imaging system according to claim 1, wherein, R1 is the radius of curvature of the object-side surface of the first lens, R2 is the radius of curvature of the image-side surface of the first lens, and R1 / R2 > 3.

5.

10. The optical imaging system according to claim 1, wherein, R3 is the radius of curvature of the object-side surface of the second lens, R4 is the radius of curvature of the image-side surface of the second lens, and R3 / R4 > 10.

11. An ultra-wide-angle optical imaging system, the optical imaging system comprising: A first lens having a negative refractive power and having a meniscus shape, the first lens having a convex object-side surface and a concave image-side surface; A second lens having a negative refractive power and having a meniscus shape, the second lens having a convex object-side surface and a concave image-side surface; A third lens having a positive refractive power; A fourth lens having a positive refractive power and a convex image-side surface; A fifth lens having a positive refractive power and a convex object-side surface; A sixth lens having a negative refractive power, a concave object-side surface and a concave image-side surface; And A seventh lens having a positive refractive power, a convex object-side surface and a convex image-side surface, Wherein, the optical imaging system includes a total of seven lenses with refractive power, and the first lens to the seventh lens are sequentially arranged from the object side towards the image side, Wherein, the third lens and the seventh lens are formed of plastics having the same optical properties as each other, and both the third lens and the seventh lens have a refractive index less than 1.535, Wherein, the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens are formed of glass, wherein, the image-side surface of the fifth lens and the object-side surface of the sixth lens are cemented to each other, and where TTL is the distance from the object surface of the first lens to the imaging surface of the image sensor, IMGH is half of the diagonal length of the imaging surface of the image sensor, and <TTL / (2 IMGH)< .

12. The optical imaging system according to claim 11, wherein, R1 is the radius of curvature of the object-side surface of the first lens, R2 is the radius of curvature of the image-side surface of the first lens, R3 is the radius of curvature of the object-side surface of the second lens, R4 is the radius of curvature of the image-side surface of the second lens, and R1 / R2 > 3.5 and R3 / R4 > 10.

13. The optical imaging system according to claim 11, wherein, The object-side surface and the image-side surface of the third lens and the seventh lens are aspherical surfaces.

14. The optical imaging system according to claim 11, wherein, The third lens includes a concave object-side surface and a convex image-side surface, and wherein, the fourth lens includes a convex object-side surface.

15. The optical imaging system according to claim 11, wherein, The object-side surfaces and the image-side surfaces of the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens are spherical surfaces.

Images