Low-distortion optical system and camera module using the same

Abstract

The application provides a low-distortion optical system and an applied camera module, which are mainly composed of eight lenses, wherein the first lens has a convex object plane and a concave image plane, and has negative optical power; the second lens has a convex object plane and a concave image plane, and has negative optical power; the third lens has a convex object plane and a concave image plane, and has negative optical power; the fourth lens has a convex object plane and a concave image plane, and has negative optical power; the fifth lens has a convex object plane and a convex image plane, and has positive optical power; the sixth lens has a convex object plane and a convex image plane, and has positive optical power; the seventh lens has a concave object plane and a convex image plane, and has negative optical power; and the eighth lens has a convex object plane and a convex image plane, and has positive optical power. Through reasonable distribution of the optical power of the lenses, the lens aberration is optimized, the imaging quality of the optical system is improved, and the characteristics of super wide angle, high definition resolution and excellent temperature characteristics are considered.

Description

Technical Field

[0001] The present application relates to the field of optical systems, and in particular to a low-distortion, high-pixel optical system used in video conferencing equipment and a camera module used therein. Background Art

[0002] With technological advancements and the needs of socioeconomic development, video transmission technology has developed rapidly, and video conferencing equipment using this technology has emerged. Currently, existing video transmission lenses typically have only around two million pixels, resulting in high image noise and poor image quality, making them difficult to process using post-processing algorithms. Summary of the Invention

[0003] This application aims to overcome the common problems of high image noise and poor imaging quality in existing optical systems or camera lenses used for video transmission lenses. On the one hand, this application provides a low-distortion, high-pixel optical system with the advantages of wide angle, small distortion and high resolution.

[0004] A low-distortion, high-pixel optical system, which is composed of 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 plane to the image plane along the optical axis;

[0005] The object side of the first lens is convex, the image side is concave, and its optical power is negative;

[0006] The object side of the second lens is convex, the image side is concave, and its optical power is negative;

[0007] The object side of the third lens is convex, the image side is concave, and its optical power is negative;

[0008] The fourth lens has a convex object side and a concave image side, and its optical power is negative;

[0009] The object side and image side of the fifth lens are both convex, and its optical power is positive;

[0010] The object side and image side of the sixth lens are both convex, and its optical power is positive;

[0011] The seventh lens has a concave object side and a convex image side, and its optical power is negative.

[0012] The object side and image side of the eighth lens are both convex surfaces, and its optical power is positive.

[0013] Preferably, each lens of the optical system meets the following conditions:

[0014] -35mm<f1<-25mm;

[0015] -8.9mm<f2<-5.8mm;

[0016] -16mm<f3<-11mm;

[0017] 15.7mm<f4<39.5mm;

[0018] 7.3mm<f5<8.5mm;

[0019] 3.9mm<f6<5.3mm;

[0020] -5.5mm<f7<-4.5mm;

[0021] 6.3mm<f8<8.6mm;

[0022] Among them, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, and f8 is the focal length of the eighth lens.

[0023] Preferably, each lens of the optical system meets the following conditions:

[0024] Nd1>1.5,Vd1<60.2;

[0025] Nd2<1.6,Vd2>53.2;

[0026] Nd3<1.6,Vd3>60;

[0027] Nd4>1.70,Vd4<50;

[0028] Nd5<1.85,Vd5>45;

[0029] Nd6<1.65,Vd6>60;

[0030] Nd7<1.9,Vd7>22;

[0031] Nd8>1.53,Vd8<57;

[0032] Wherein, Nd1 is the refractive index of the first lens element, and Vd1 is the Abbe number of the first lens element; Nd2 is the refractive index of the second lens element, and Vd2 is the Abbe number of the second lens element; Nd3 is the refractive index of the third lens element, and Vd3 is the Abbe number of the third lens element; Nd4 is the refractive index of the fourth lens element, and Vd4 is the Abbe number of the fourth lens element; Nd5 is the refractive index of the fifth lens element, and Vd5 is the Abbe number of the fifth lens element; Nd6 is the refractive index of the sixth lens element, and Vd6 is the Abbe number of the sixth lens element; Nd7 is the refractive index of the seventh lens element, and Vd7 is the Abbe number of the seventh lens element; Nd8 is the refractive index of the eighth lens element, and Vd8 is the Abbe number of the eighth lens element.

[0033] Preferably, the maximum angle CRA of the full-field chief ray of the optical system incident on the image plane satisfies: CRA <17°.

[0034] Preferably, the curvature radii R of the object surface and the image surface side of the second lens both satisfy: R > 0;

[0035] Preferably, the total optical length TTL of the optical system satisfies: TTL ≤ 31 mm.

[0036] Preferably, the second lens is a plastic lens, and the third lens is a glass lens.

[0037] Preferably, the F number of the optical system is: 1.9≤F number≤2.3

[0038] Preferably, the aperture is provided between the fifth lens and the sixth lens, and the sixth lens and the seventh lens are bonded to each other to form a combined lens.

[0039] On the other hand, an embodiment of the present application further provides a camera module, which includes at least an optical lens, in which the above-mentioned low-distortion optical system is installed.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] The present invention provides a low-distortion optical system and a camera module used therein, which is mainly composed of 8 lenses. The object side of the first lens is convex, the image side is concave, and its optical power is negative; the object side of the second lens is convex, the image side is concave, and its optical power is negative; the object side of the third lens is convex, the image side is concave, and its optical power is negative; the object side of the fourth lens is convex, the image side is concave, and its optical power is negative; the object side and the image side of the fifth lens are both convex, and its optical power is negative. The focal power is positive; the object side and image side of the sixth lens are both convex, and its optical focal power is positive; the object side of the seventh lens is concave, and the image side is convex, and its optical focal power is negative; the object side and image side of the eighth lens are both convex, and its optical focal power is positive. The number of lenses is reasonable and the structure is simple. By reasonably allocating the optical power of the lenses, optimizing lens aberrations, and improving the imaging quality of the optical system, taking into account the characteristics of ultra-wide angle, high-definition resolution, and excellent temperature characteristics, it has huge potential in the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments.

[0043] Figure 1 Schematic diagram of the structure of the optical system or camera module of Example 1 of the present application;

[0044] Figure 2 1 is a graph showing astigmatism and distortion of the optical system or camera module according to Example 1 of the present application;

[0045] Figure 3 is an MTF curve diagram of the optical system or camera module of Example 1 of the present application;

[0046] Figure 4 2 is a schematic structural diagram of an optical system or camera module according to embodiment 2 of the present application;

[0047] Figure 5 is an astigmatism and distortion curve diagram of the optical system or camera module of Example 2 of the present application;

[0048] Figure 6 : is an MTF curve diagram of the optical system or camera module of Example 2 of the present application;

[0049] Figure 7 Schematic diagram of the structure of the optical system or camera module according to Example 3 of the present application;

[0050] Figure 8 3 is a graph showing astigmatism and distortion of the optical system or camera module according to Example 3 of the present application;

[0051] Figure 9 This is the MTF curve diagram of the optical system or camera module of Example 3 of the present application. DETAILED DESCRIPTION

[0052] like Figure 1-9 As shown, the present application provides a low-distortion optical system, which is composed of a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, an aperture 9, a sixth lens 6, a seventh lens 7, an eighth lens 8, and an infrared filter 10 in sequence along the optical axis from the object plane to the image plane.

[0053] The object side of the first lens is convex, the image side is concave, and its optical power is negative;

[0054] The object side of the second lens is convex, the image side is concave, and its optical power is negative;

[0055] The object side of the third lens is convex, the image side is concave, and its optical power is negative;

[0056] The fourth lens has a convex object side and a concave image side, and its optical power is negative;

[0057] The object side and image side of the fifth lens are both convex, and its optical power is positive;

[0058] The object side and image side of the sixth lens are both convex, and its optical power is positive;

[0059] The seventh lens has a concave object side and a convex image side, and its optical power is negative.

[0060] The object side and image side of the eighth lens are both convex, and its optical power is positive;

[0061] The present invention provides a low-distortion optical system and a camera module used therein, which is mainly composed of 8 lenses. The object side of the first lens is convex, the image side is concave, and its optical power is negative; the object side of the second lens is convex, the image side is concave, and its optical power is negative; the object side of the third lens is convex, the image side is concave, and its optical power is negative; the object side of the fourth lens is convex, the image side is concave, and its optical power is negative; the object side and the image side of the fifth lens are both convex, and its optical power is negative. The focal power is positive; the object side and image side of the sixth lens are both convex, and its optical focal power is positive; the object side of the seventh lens is concave, and the image side is convex, and its optical focal power is negative; the object side and image side of the eighth lens are both convex, and its optical focal power is positive. The number of lenses is reasonable and the structure is simple. By reasonably allocating the optical power of the lenses, optimizing lens aberrations, and improving the imaging quality of the optical system, taking into account the characteristics of ultra-wide angle, high-definition resolution, and excellent temperature characteristics, it has huge potential in the market.

[0062] Furthermore, as a preferred embodiment of the present invention but not limiting, each lens of the optical system satisfies the following conditions, wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, and f8 is the focal length of the eighth lens:

[0063] (1) -35mm<f1<-25mm, by constraining the effective focal length of the first lens E1 within a reasonable range, the distortion of the system is controlled, and the imaging center has a higher angular resolution;

[0064] (2) -8.9mm<f2<-5.8mm. By constraining the effective focal length of the second lens E2 within a reasonable range, the configured optical system has excellent temperature characteristics, thereby improving the imaging stability of the optical system at high and low temperatures and improving the imaging quality;

[0065] (3) -16mm<f3<-11mm, by constraining the effective focal length of the third lens E3 within a reasonable range, the spherical aberration of the system is fine-tuned and controlled, thereby effectively improving the imaging quality of the system;

[0066] (4) 15.7mm<f4<39.5mm. By properly controlling the effective focal length of the fourth lens E4 within a reasonable range, the system's astigmatism and field curvature are well corrected, effectively improving the system's imaging quality.

[0067] (5) 7.3mm<f5<8.5mm. By constraining the effective focal length of the fifth lens E5 within a reasonable range, the configured optical system has excellent temperature characteristics, thereby improving the imaging stability of the optical system at high and low temperatures and improving the imaging quality;

[0068] (6) 3.9mm<f6<5.3mm, by constraining the effective focal length of the sixth lens E6 to a reasonable range, lens aberrations are optimized and analytical performance is improved;

[0069] (7) -5.5mm<f7<-4.5mm. By constraining the effective focal length of the seventh lens E7 within a reasonable range, good optical performance can be guaranteed, lens aberrations can be optimized, analytical performance can be improved, and the viewing angle can be further guaranteed.

[0070] (8) 6.3mm<f8<8.6mm. By constraining the effective focal length of the eighth lens E8 within a reasonable range, the internal aberrations of the optical lens can be balanced, which in turn helps to adjust the field curvature and astigmatism at the imaging edge of the optical lens, thereby meeting the imaging quality of the optical lens for the surrounding environment.

[0071] Preferably, the refractive index Nd1 and the Abbe constant Vd1 of the material of the first lens E1 satisfy the following requirements: Nd1>1.5, Vd1<60.2. This design can effectively reduce chromatic aberration, optimize lens aberration, and thereby effectively improve the imaging quality of the system.

[0072] Preferably, the refractive index Nd2 and the Abbe number Vd2 of the material of the second lens E2 satisfy the following conditions: Nd2 < 1.6, Vd2 > 53.2, which can ensure good optical performance, further ensure the viewing angle, improve the lens resolution and reduce distortion.

[0073] Preferably, the refractive index Nd3 and the Abbe number Vd3 of the material of the third lens E3 satisfy the following: Nd3 < 1.6, Vd3 > 60. This design can effectively reduce chromatic aberration, optimize lens aberration, and thereby effectively improve the imaging quality of the system.

[0074] Preferably, the refractive index Nd4 and the Abbe number Vd4 of the material of the fourth lens element E4 satisfy the following conditions: Nd4>1.70, Vd4<50, which can ensure good optical performance, further ensure the viewing angle, improve the lens resolution and reduce distortion.

[0075] Preferably, the refractive index Nd5 and the Abbe number Vd5 of the material of the fifth lens element E5 satisfy the following conditions: Nd5 < 1.85, Vd5 > 45. This design can effectively reduce chromatic aberration, optimize lens aberrations, and thereby effectively improve the imaging quality of the system.

[0076] Preferably, the refractive index Nd6 and the Abbe number Vd6 of the material of the sixth lens element E6 satisfy the following conditions: Nd6 < 1.65, Vd6 > 60. This design can effectively reduce chromatic aberration, optimize lens aberrations, and thereby effectively improve the imaging quality of the system.

[0077] Preferably, the refractive index Nd7 and the Abbe number Vd7 of the material of the seventh lens element E7 satisfy the following conditions: Nd7 < 1.9, Vd7 > 22, which can ensure good optical performance, further ensure the viewing angle, improve the lens resolution, and reduce distortion.

[0078] Preferably, the refractive index Nd8 and the Abbe number Vd8 of the material of the eighth lens element E8 satisfy the following conditions: Nd8>1.53, Vd8<57, which can ensure good optical performance, further ensure the viewing angle, improve the lens resolution, and reduce distortion.

[0079] Furthermore, as a preferred embodiment of the present invention but not a limitation thereof, the maximum angle CRA of the full-field chief ray incident on the image plane of the optical system satisfies: CRA < 17°. This design can make the CRA of the lens more compatible with the CRA of the chip, thereby improving the photosensitivity efficiency of the chip.

[0080] Furthermore, as a preferred embodiment of the present invention but not limitation, the curvature radii R of the object side and the image side of the second lens both satisfy: R > 0. By controlling the R values ​​of the object side and the image side of the second lens, the distortion can be effectively calibrated and the imaging quality of the system can be improved.

[0081] Furthermore, as a preferred embodiment of the present invention but not limitation, the total optical length TTL of the optical system satisfies: TTL ≤ 31 mm. This design can provide sufficient space between the lenses to improve the performance of the system.

[0082] Furthermore, as a preferred embodiment of the present invention but not limiting, the second lens is a plastic lens and the third lens is a glass lens. This design can improve the performance at high and low temperatures;

[0083] Furthermore, as a preferred embodiment of the present invention but not limiting, the F number and FOV of the optical system satisfy the following conditions: 1.9≤F number≤2.3. The configuration of a large aperture can increase the amount of light entering the optical system and achieve higher imaging quality.

[0084] Furthermore, as a preferred embodiment of the present invention but not a limitation thereof, the sixth lens element and the seventh lens element are cemented together to form a composite lens. The refractive index Nd6 and Abbe number Vd6 of the sixth lens element, as well as the refractive index Nd7 and Abbe number Vd7 of the seventh lens element, satisfy the following conditions: Nd6 < 1.65, Vd6 > 60; and Nd7 < 1.9, Vd7 > 22. This design increases the difference between the refractive index and Abbe number of the lenses, effectively reducing chromatic aberration.

[0085] Specifically, as a preferred embodiment of the present invention but not limiting, Figure 1-3 As shown, in this embodiment 1, the focal length f1 of the first lens 1 is -28.24 mm, the focal length f2 of the second lens 2 is -7.32 mm, the focal length f3 of the third lens 3 is -15.92 mm, the focal length f4 of the fourth lens 4 is 34.95 mm, the focal length f5 of the fifth lens 5 is 8.27 mm, the focal length f6 of the sixth lens 6 is 4.63 mm, the focal length f7 of the seventh lens 7 is -5.09 mm, the focal length f8 of the eighth lens 8 is 7.65 mm, and the total optical length TTL is 30 mm. The surface type, curvature radius, thickness and material parameters of each lens are shown in Table 1:

[0086] Table 1: Basic parameters of the optical system of Example 1

[0087]

[0088] In Table 1 above, along the optical axis from the object plane to the image plane, OBJ is the object plane; S1 and S2 correspond to the two surfaces of the first lens 1; S3 and S4 correspond to the two surfaces of the second lens 2; S5 and S6 correspond to the two surfaces of the third lens 3; S7 and S8 correspond to the two surfaces of the fourth lens 4; S9 and S10 correspond to the two surfaces of the fifth lens 5; S12 and S13 correspond to the two surfaces of the sixth lens 6; S13 and S14 correspond to the two surfaces of the seventh lens 7; S15 and S16 correspond to the two surfaces of the eighth lens 8; STO is the position of the aperture; S17 and S18 correspond to the two surfaces of the filter; and IMA corresponds to the image plane.

[0089] Furthermore, in Table 1, the object side and image side of any one of the second lens 2 and the eighth lens 8 are aspherical surfaces. The surface shape of each aspherical lens can be defined by, but not limited to, the following aspherical surface formula:

[0090]

[0091] Where x is the distance from the corresponding point on the aspheric surface to the plane tangent to the vertex of the surface, h is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the aspheric vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspheric surface shape formula. Table 2 shows the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 for various aspheric surfaces that can be used in Example 1.

[0092] Table 2: Aspheric surface related values ​​of the lens surface of Example 1

[0093]

[0094] Figure 2 The astigmatism and distortion curves of the optical imaging lens of Example 1 are shown. Astigmatism represents meridional image curvature and sagittal image curvature, and distortion represents the distortion magnitude corresponding to different image heights. Figure 3 The MTF curve of the optical imaging lens of Example 1 is shown, which represents the MTF values ​​in the meridian and sagittal directions of different fields of view at different spatial frequencies. Figure 2 and Figure 3 It can be seen that the optical imaging system provided in Example 1 can achieve good imaging quality and has higher imaging quality.

[0095] Specifically, as a preferred embodiment of the present invention but not limiting, Figure 4-6 As shown, in this embodiment 2, the focal length f1 of the first lens 1 is -29.40 mm, the focal length f2 of the second lens 2 is -7.47 mm, the focal length f3 of the third lens 3 is -12.44 mm, the focal length f4 of the fourth lens 4 is 24.05 mm, the focal length f5 of the fifth lens 5 is 8.26 mm, the focal length f6 of the sixth lens 6 is 4.64 mm, the focal length f7 of the seventh lens 7 is -5.03 mm, the focal length f8 of the eighth lens 8 is 7.7 mm, and the total optical length TTL is 30 mm. The surface type, curvature radius, thickness and material parameters of each lens are shown in Table 3:

[0096] Table 3: Basic parameters of the optical system of Example 2

[0097]

[0098] In Table 3 above, along the optical axis from the object plane to the image plane, OBJ is the object plane; S1 and S2 correspond to the two surfaces of the first lens 1; S3 and S4 correspond to the two surfaces of the second lens 2; S5 and S6 correspond to the two surfaces of the third lens 3; S7 and S8 correspond to the two surfaces of the fourth lens 4; S9 and S10 correspond to the two surfaces of the fifth lens 5; S12 and S13 correspond to the two surfaces of the sixth lens 6; S13 and S14 correspond to the two surfaces of the seventh lens 7; S15 and S16 correspond to the two surfaces of the eighth lens 8; STO is the position of the aperture; S17 and S18 correspond to the two surfaces of the filter; and IMA corresponds to the image plane.

[0099] Furthermore, in Table 3, the object side and image side of any one of the second lens 2 and the eighth lens 8 are aspherical surfaces. The surface shape of each aspherical lens can be defined by, but not limited to, the following aspherical surface formula:

[0100]

[0101] Where x is the distance from the corresponding point on the aspheric surface to the plane tangent to the vertex of the surface, h is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the aspheric vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspheric surface shape formula. Table 4 shows the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 for various aspheric surfaces that can be used in Example 2.

[0102] Table 4: Aspheric surface related values ​​of the lens surface of Example 2

[0103]

[0104] Figure 5 The astigmatism and distortion curves of the optical imaging lens of Example 2 are shown. Astigmatism represents meridional image curvature and sagittal image curvature, and distortion represents the distortion magnitude corresponding to different image heights. Figure 6 The MTF curve of the optical imaging lens of Example 2 is shown, which represents the MTF values ​​in the meridian and sagittal directions of different fields of view at different spatial frequencies. Figure 5 and Figure 6 It can be seen that the optical imaging system provided in Example 2 can achieve good imaging quality and has higher imaging quality.

[0105] Specifically, as a preferred embodiment of the present invention but not limiting, Figure 7-9 As shown, in this embodiment 3, the focal length f1 of the first lens 1 is -27.30 mm, the focal length f2 of the second lens 2 is -7.65 mm, the focal length f3 of the third lens 3 is -12.27 mm, the focal length f4 of the fourth lens 4 is 22.78 mm, the focal length f5 of the fifth lens 5 is 8.26 mm, the focal length f6 of the sixth lens 6 is 4.62 mm, the focal length f7 of the seventh lens 7 is -4.85 mm, the focal length f8 of the eighth lens 8 is 8 mm, and the total optical length TTL is 30.1 mm. The surface type, curvature radius, thickness and material parameters of each lens are shown in Table 5:

[0106] Table 5: Basic parameters of the optical system of Example 3

[0107]

[0108] In Table 5 above, along the optical axis from the object plane to the image plane, OBJ is the object plane; S1 and S2 correspond to the two surfaces of the first lens 1; S3 and S4 correspond to the two surfaces of the second lens 2; S5 and S6 correspond to the two surfaces of the third lens 3; S7 and S8 correspond to the two surfaces of the fourth lens 4; S9 and S10 correspond to the two surfaces of the fifth lens 5; S12 and S13 correspond to the two surfaces of the sixth lens 6; S13 and S14 correspond to the two surfaces of the seventh lens 7; S15 and S16 correspond to the two surfaces of the eighth lens 8; STO is the position of the aperture; S17 and S18 correspond to the two surfaces of the filter; and IMA corresponds to the image plane.

[0109] Furthermore, in Table 5, the object side and image side of any one of the second lens 2 and the eighth lens 8 are aspherical surfaces. The surface shape of each aspherical lens can be defined by, but not limited to, the following aspherical surface formula:

[0110]

[0111] Where x is the distance from the corresponding point on the aspheric surface to the plane tangent to the vertex of the surface, h is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the aspheric vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspheric surface shape formula. Table 6 shows the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 for various aspheric surfaces that can be used in Example 3.

[0112] Table 6: Aspheric surface related values ​​of the lens surface of Example 3

[0113]

[0114] Figure 8 The astigmatism and distortion curves of the optical imaging lens of Example 3 are shown. Astigmatism represents meridional image curvature and sagittal image curvature, and distortion represents the distortion magnitude corresponding to different image heights. Figure 9 The MTF curve of the optical imaging lens of Example 3 is shown, which represents the MTF values ​​in the meridian and sagittal directions of different fields of view at different spatial frequencies. Figure 8 and Figure 9 It can be seen that the optical imaging system provided in Example 3 can achieve good imaging quality and has higher imaging quality.

[0115] Furthermore, in Examples 1-3, the basic data are as follows:

[0116] Table 7: Basic data of Examples 1-3

[0117]

[0118] The application discloses a camera module, which comprises at least an optical lens, and the low-distortion optical system is installed in the optical lens.

[0119] The above is one or more embodiments provided in combination with specific contents, and does not mean that the specific implementation of the application is limited to the description. Any approximation, similarity or replacement of the method and structure of the application, or any technical deduction or replacement under the premise of the concept of the application, should be regarded as the protection scope of the application.

Claims

1. A low-distortion optical system, comprising, in order from the object plane to the image plane along the optical axis, 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, characterized in that: The object side of the first lens is convex, the image side is concave, and its optical power is negative; The object side of the second lens is convex, the image side is concave, and its optical power is negative; The object side of the third lens is convex, the image side is concave, and its optical power is negative; The fourth lens has a convex object side and a concave image side, and its optical power is negative; The object side and image side of the fifth lens are both convex, and its optical power is positive; The object side and image side of the sixth lens are both convex, and its optical power is positive; The seventh lens has a concave object side and a convex image side, and its optical power is negative. The object side and image side of the eighth lens are both convex, and its optical power is positive; Each lens of the optical system meets the following conditions: -35mm<f1<-25mm; -8.9mm<f2<-5.8mm; -16mm<f3<-11mm; 15.7mm<f4<39.5mm; 7.3mm<f5<8.5mm; 3.9mm<f6<5.3mm; -5.5mm<f7<-4.5mm; 6.3mm<f8<8.6mm; Among them, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, f7 is the focal length of the seventh lens, and f8 is the focal length of the eighth lens.

2. The low-distortion optical system according to claim 1, wherein: Each lens of the optical system meets the following conditions: Nd1>1.5,Vd1<60.2; Nd2<1.6,Vd2>53.2; Nd3<1.6,Vd3>60; Nd4>1.70,Vd4<50; Nd5<1.85,Vd5>45; Nd6<1.65,Vd6>60; Nd7<1.9,Vd7>22; Nd8>1.53,Vd8<57; Wherein, Nd1 is the refractive index of the first lens element, and Vd1 is the Abbe number of the first lens element; Nd2 is the refractive index of the second lens element, and Vd2 is the Abbe number of the second lens element; Nd3 is the refractive index of the third lens element, and Vd3 is the Abbe number of the third lens element; Nd4 is the refractive index of the fourth lens element, and Vd4 is the Abbe number of the fourth lens element; Nd5 is the refractive index of the fifth lens element, and Vd5 is the Abbe number of the fifth lens element; Nd6 is the refractive index of the sixth lens element, and Vd6 is the Abbe number of the sixth lens element; Nd7 is the refractive index of the seventh lens element, and Vd7 is the Abbe number of the seventh lens element; Nd8 is the refractive index of the eighth lens element, and Vd8 is the Abbe number of the eighth lens element.

3. The low-distortion optical system according to claim 1, wherein: The maximum angle CRA of the full-field chief ray incident on the image plane of this optical system satisfies: CRA < 17°.

4. The low-distortion optical system according to claim 1, wherein: The curvature radii R of the object surface and the image surface side of the second lens both satisfy: R > 0.

5. The low-distortion optical system according to claim 1, wherein: The total optical length TTL of the optical system satisfies: TTL ≤ 31 mm.

6. The low-distortion optical system according to claim 1, wherein: The second lens is a plastic lens, and the third lens is a glass lens.

7. The low-distortion optical system according to claim 1, wherein: The F number of the optical system is: 1.9≤F number≤2.

3.

8. The low-distortion optical system according to claim 1, wherein: The aperture is arranged between the fifth lens and the sixth lens.

9. The low-distortion optical system according to claim 1, wherein: The sixth lens and the seventh lens are cemented together to form a combined lens.

10. A camera module, comprising at least an optical lens, characterized in that: The optical lens is equipped with the low-distortion optical system according to any one of claims 1 to 9.

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