A large aperture lens based on DOE surface

Abstract

The present invention proposes a large aperture lens based on a DOE surface type, wherein the optical system of the lens comprises a first lens with negative optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with negative optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with positive optical power, and a tenth lens with positive optical power; wherein the eighth lens is a meniscus lens with positive optical power, the front surface of which is described by the DOE surface type, and the rear surface is a spherical surface; the focal length of the lens of the present invention is 9 mm, the aperture F number reaches 1.0, and the modulation transfer function is above 35% at 250 line pairs / mm, so that the lens can achieve a larger effective aperture while maintaining high image quality.

Description

Technical Field

[0001] The invention relates to the field of optical lenses and optical design, in particular to a large aperture lens based on a DOE surface type. Background Art

[0002] With the development of digital imaging technology, the demand for high-quality lenses is increasing, especially in professional photography and high-end film production. Photographers and directors pursue clearer and brighter image effects. Due to various limitations, traditional lenses will encounter various problems such as chromatic aberration and distortion when increasing the aperture. In addition, when the aperture is larger, the image quality may deteriorate due to the increase in the area of ​​the lens through which light passes. Therefore, the development of a new lens with high imaging quality and large aperture characteristics has become an urgent problem to be solved in the industry. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the present invention proposes a large aperture lens based on a DOE surface type. The lens adopts an advanced diffractive optical element DOE surface type as a key component, and optimizes imaging performance by precisely controlling the light propagation path. The DOE surface type lens can achieve a larger effective aperture while maintaining high image quality, thereby obtaining a shallower depth of field. In addition, this new lens also has lower dispersion and distortion rate, ensuring high-definition imaging from the center to the edge, and specifically realizes a focal length of 9.0mm, an F number of 1.0, a total system length of 154mm, a full field angle of the system of 60°, and an MTF of the system of more than 0.35 at 250lp / mm.

[0004] The technical solution of the present application is: a large aperture lens based on a DOE surface type, wherein the focal length of the lens is 9 mm, the aperture F number is 1.0, and the modulation transfer function is above 35% at 250 line pairs. The lens comprises, in sequence from the object side to the image side of the optical axis: a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with negative optical power, and a tenth lens with positive optical power; wherein the eighth lens is a meniscus lens with positive optical power, the front surface of which is described using the DOE surface type, and the rear surface is a spherical surface.

[0005] The optical system of the lens satisfies the relationship: 15<(TTL / F) / FNUM<20, wherein F is the effective focal length of the optical system, TTL is the length of the optical system, and FNUM is the relative aperture of the optical system. By limiting the relationship between the total optical length, focal length and relative aperture of the optical lens, the optical system can have a greater depth of field while ensuring the length of the optical system.

[0006] Furthermore, the refractive index of the fifth lens is in the range of 1.5 to 1.8; the center thickness of the sixth lens is in the range of 6.5 to 8 mm, and the refractive index is in the range of 1.8 to 2.0; the center thickness of the seventh lens is in the range of 7 to 8.5 mm, and the refractive index is in the range of 1.6 to 1.8; the center thickness of the eighth lens is in the range of 5 to 6 mm, and the refractive index is in the range of 1.45 to 1.55. The combination of materials with different refractive indices has a better correction effect on the primary aberration of the optical system.

[0007] Furthermore, the half field angle w of the optical system of the lens is 30°, so that the optical system obtains a relatively larger field angle.

[0008] Furthermore, the back focus BACK of the optical system satisfies the relationship: 7.9mm≦BACK≦8.3mm, making the structure of the optical system more reasonable.

[0009] Furthermore, the eighth lens of the optical system satisfies the relationship: 8.0≦|f / F|≦8.5, wherein f is the effective focal length of the eighth lens, and F is the effective focal length of the optical system, so as to better control the eighth lens.

[0010] Furthermore, the eighth lens of the system satisfies the relationship: 2.3≦|d / H|≦2.8, wherein d is the aperture value of the eighth lens, and H is the thickness of the eighth lens. Selecting a more reasonable aperture and thickness will facilitate subsequent processing.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The optical system of the present invention adopts an optical system designed based on a large aperture lens of a DOE surface type, which achieves a larger effective aperture while maintaining high image quality; the system parameters achieved by the present invention are: the system focal length reaches 9.0 mm, the F number reaches 1.0, the total length of the system reaches 154 mm, the full field angle of the system reaches 60°, and the MTF of the system can reach more than 0.35 at 250lp / mm, thereby achieving good imaging effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of an optical lens disclosed in the first embodiment of a large aperture lens based on a DOE surface type in the present application;

[0014] Figure 2 It is a modulation transfer function analysis diagram disclosed in the first embodiment of a large aperture lens based on a DOE surface type of the present application;

[0015] Figure 3This is a full-field root mean square spot size diagram disclosed in the first embodiment of a large aperture lens based on a DOE surface type in the present application;

[0016] Figure 4 It is a structural schematic diagram of an optical lens disclosed in the second embodiment of a large aperture lens based on a DOE surface type in the present application;

[0017] Figure 5 It is a modulation transfer function analysis diagram disclosed in the second embodiment of a large aperture lens based on a DOE surface type of the present application;

[0018] Figure 6 This is a full-field root mean square spot size diagram disclosed in the second embodiment of a large aperture lens based on a DOE surface type in the present application;

[0019] Figure 7 It is a structural schematic diagram of an optical lens disclosed in the third embodiment of a large aperture lens based on a DOE surface type in the present application;

[0020] Figure 8 It is a modulation transfer function analysis diagram disclosed in the third embodiment of a large aperture lens based on a DOE surface type of the present application;

[0021] Fig. 9 This is a full-field root mean square spot size diagram disclosed in the third embodiment of a large aperture lens based on a DOE surface type in the present application. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the present invention, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation. In addition, in addition to being used to indicate an orientation or positional relationship, some of the above terms may also be used to indicate other meanings. For example, the term "upper" may also be used to indicate a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to the specific circumstances. In addition, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0024] In the example of the present invention, the lens includes, in sequence from the object side to the image side of the optical axis: a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with negative optical power, and a tenth lens with positive optical power. The use of reasonable optical power matching can effectively control the light propagation path, reduce aberrations, ensure that each optical element works in the best state, and reduce manufacturing costs and complexity. Reasonable optical power matching can also enhance the adaptability of the optical system to different usage scenarios and needs.

[0025] The eighth lens is a positive power meniscus lens, the front surface of which is described by a DOE surface shape, and the rear surface is a spherical surface. The surface shape is defined by the following formula:

[0026] The general form for a rotationally symmetric DOE lens can be expressed as:

[0027]

[0028] Among them, C = 1 / R, R is the radius; ρ is the radial coordinate; A2, A4, A6... are the high-order coefficients of the DOE surface. Compared with the traditional rotationally symmetric spherical and aspherical surfaces, the DOE surface has great design freedom and strong aberration balance and correction capabilities. Through the reasonable use of the DOE surface, this system finally achieved a focal length of 9.0mm, an F number of 1.0, a total system length of 154mm, a full field of view of 60°, and an MTF of 0.35 or above at 250lp / mm.

[0029] The entire optical system of the present invention will be described in detail below by combining embodiments, specific parameters and illustrations of the drawings.

[0030] Example 1, specifically, taking the lens of Example 1 as an example, the system parameters of the optical system are focal length f=9.0 mm, aperture number FNO=1.0, maximum field of view half angle HFOV=30°, and total length of the optical system TTL=154.4 mm.

[0031] like Figure 1 As shown in FIG. 1 , the large aperture lens based on the DOE surface type is, in order of the optical path, a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with negative optical power, and a tenth lens with positive optical power. Among them, S1 is the object side of the first lens, S2 is the image side of the first lens, S3 is the object side of the second lens, S4 is the image side of the second lens, S5 is the object side of the third lens, S6 is the image side of the third lens, S7 is the object side of the fourth lens, S8 is the image side of the fourth lens, S9 is the object side of the fifth lens, S10 is the image side of the fifth lens, S11 is the object side of the sixth lens, S12 is the image side of the sixth lens, S13 is the object side of the seventh lens, S14 is the image side of the seventh lens, S15 is the object side of the eighth lens, S16 is the image side of the eighth lens, S17 is the object side of the ninth lens, S18 is the image side of the ninth lens, S19 is the object side of the tenth lens, S20 is the image side of the tenth lens, the dotted line between S12 and S13 is the aperture, and the dotted line on the right side of S20 is the image plane.

[0032] The curvature radius R, thickness d, refractive index Nd and Abbe number Vd of each surface of this optical system are shown in Table 1.

[0033] Table 1

[0034] surface Radius of curvature thickness Refractive Index Abbe number 1 220.32022 6.33661 1.76545 51.18 2 18.97066 9.48211 3 -22.32412 8.01655 1.64959 32.6 4 unlimited 3.33964 5 -57.00705 8.01686 1.9 25.38 6 -36.88405 1 7 -3896.9442 8.03952 1.72273 55.79 8 -57.60511 44.03296 9 65.25599 7.93792 1.501 77.46 10 -102.11636 1 11 36.58526 6.58725 1.9 22.55 12 23.79073 10.62283 Aperture 3.55539 13 40.13705 8.0338 1.65348 62.56 14 1029.59466 7.56854 15 DOE 5.45671 1.501 77.46 16 28.6538 1 17 21.18578 4.84897 1.9 22.55 18 11.2999 2.41181 19 13.19534 7.15146 1.71272 56.77 20 256.43537 7.99991 Image plane unlimited 0

[0035] Among them, the radius of curvature in Table 1 is the radius of curvature of the object side or image side of the corresponding surface number at the optical axis. The first value in the "Thickness" parameter column of the lens is the thickness of the lens on the optical axis, and the second value is the distance from the image side of the lens to the next surface on the optical axis. The direction from the object side of the first lens to the image side of the last lens is assumed to be the positive direction of the optical axis. The units of the radius of curvature and thickness in Table 1 are both mm. And the refractive index in Table 1 is obtained at a reference wavelength of 0.5876um.

[0036] In Example 1, the front surface of the eighth lens adopts a DOE surface shape, and only the second-order term is selected for the DOE surface shape, and the second-order term coefficient is 80.7206925, the radius R value is 0.0560414702, and the radial coordinate ρ value is 0.5876. The use of the DOE surface shape greatly improves the imaging quality of the optical system, and at the same time, only the use of the second-order term coefficient reduces the processing difficulty of the lens.

[0037] See also Figure 2 , Figure 2 is a modulation function analysis diagram of the optical system of Example 1, wherein: Figure 2 The modulation function analysis diagram of the optical system in the first embodiment at 250 line pairs / mm is shown, wherein the diffraction limits of the meridional field of view and the sagittal field of view coincide, and the diffraction transfer functions of the meridional field of view and the sagittal field of view of 0 field of view coincide. Figure 2 In the figure, the horizontal axis along the X-axis represents the line pair value in mm, and the vertical axis along the Y-axis represents the modulation transfer function value; Figure 2 It can be seen from the figure that the modulation transfer function of the optical system in the first embodiment is above 35% at 250 line pairs / mm, indicating that the imaging quality of the optical system in this embodiment is good.

[0038] See also Figure 3 , Figure 3 is a diagram of the root mean square spot size of the full field of view of the optical system in Example 1, wherein the abscissa along the X-axis direction represents the relative field of view, and the ordinate along the Y-axis direction represents the root mean square size; Figure 3 It can be seen that under the full field of view, the root mean square size of the optical system is within 0.0025 mm, indicating that the various aberrations of the optical system in this embodiment are well corrected.

[0039] Please refer to Figure 2 , Figure 3 It can be seen that the modulation transfer function of the optical system in Example 1 is above 35% at 250 line pairs / mm, and the root mean square size is within 0.0025mm. It can be seen that the optical system has a good correction effect on various aberrations and has good imaging quality.

[0040] Example 2. Specifically, taking the lens of Example 2 as an example, the system parameters of the optical system are focal length f=9.0 mm, aperture number FNO=1.0, maximum field of view half angle HFOV=30°, and total length of the optical system TTL=154.0 mm.

[0041] like Figure 4 As shown in FIG. 1 , the large aperture lens based on the DOE surface type is, in order of the optical path, a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with negative optical power, and a tenth lens with positive optical power. Among them, S1 is the object side of the first lens, S2 is the image side of the first lens, S3 is the object side of the second lens, S4 is the image side of the second lens, S5 is the object side of the third lens, S6 is the image side of the third lens, S7 is the object side of the fourth lens, S8 is the image side of the fourth lens, S9 is the object side of the fifth lens, S10 is the image side of the fifth lens, S11 is the object side of the sixth lens, S12 is the image side of the sixth lens, S13 is the object side of the seventh lens, S14 is the image side of the seventh lens, S15 is the object side of the eighth lens, S16 is the image side of the eighth lens, S17 is the object side of the ninth lens, S18 is the image side of the ninth lens, S19 is the object side of the tenth lens, S20 is the image side of the tenth lens, the dotted line between S12 and S13 is the aperture, and the dotted line on the right side of S20 is the image plane.

[0042] The curvature radius R, thickness d, refractive index Nd and Abbe number Vd of each surface of this optical system are shown in Table 2.

[0043] Table 2

[0044] surface Radius of curvature thickness Refractive Index Abbe number 1 305.81523 6.43107 1.7519 52.94 2 19.22994 9.53528 3 -22.59041 7.84725 1.64491 32.99 4 unlimited 3.25891 5 -59.11544 7.90834 1.9 26.32 6 -37.2571 1 7 -3171.70288 8.04926 1.71899 56.16 8 -57.614 45.55807 9 64.7366 8.01938 1.501 77.46 10 -108.10462 1.00059 11 36.35217 6.52364 1.89171 22.71 12 23.79898 11.18299 Aperture 1.48686 13 40.68291 8.01635 1.65045 62.86 14 997.61445 7.33976 15 DOE 5.41764 1.501 77.46 16 29.23263 1.02472 17 21.1236 4.91521 1.9 23.06 18 11.31806 2.15285 19 13.13743 7.37565 1.69882 58.13 20 276.21177 7.9999 Image plane unlimited

[0045] Among them, the radius of curvature in Table 2 is the radius of curvature of the object side or image side of the corresponding surface number at the optical axis. The first value in the "Thickness" parameter column of the lens is the thickness of the lens on the optical axis, and the second value is the distance from the image side of the lens to the next surface on the optical axis. The direction from the object side of the first lens to the image side of the last lens is assumed to be the positive direction of the optical axis. The units of the radius of curvature and thickness in Table 2 are both mm. And the refractive index in Table 2 is obtained at a reference wavelength of 0.5876um.

[0046] In Example 2, the front surface of the eighth lens adopts a DOE surface shape, and only the second-order term is selected for the DOE surface shape, and the second-order term coefficient is 80.7206925, the radius R value is 0.0560414702, and the radial coordinate ρ value is 0.5876. The use of the DOE surface shape greatly improves the imaging quality of the optical system, and only the use of the second-order term coefficient reduces the processing difficulty of the lens.

[0047] See also Figure 5 , Figure 5 The modulation function analysis diagram of the optical system of Example 2 is shown, wherein: Figure 5 The modulation function analysis diagram of the optical system in Example 2 at 250 line pairs / mm is shown, wherein the diffraction limits of the meridional field of view and the sagittal field of view coincide, and the diffraction transfer functions of the meridional field of view and the sagittal field of view of 0 field of view coincide. Figure 5 In the figure, the horizontal axis along the X-axis represents the line pair value in mm, and the vertical axis along the Y-axis represents the modulation transfer function value; Figure 5 It can be seen from the figure that the modulation transfer function of the optical system in Example 2 is above 35% at 250 line pairs / mm, indicating that the imaging quality of the optical system in this example is good.

[0048] See also Figure 6 , Figure 6 is a diagram of the root mean square spot size of the full field of view of the optical system in Example 2, wherein the abscissa along the X-axis direction represents the relative field of view, and the ordinate along the Y-axis direction represents the root mean square size; Figure 6 It can be seen that under the full field of view, the root mean square size of the optical system is within 0.0025 mm, indicating that the various aberrations of the optical system in this embodiment are well corrected.

[0049] Please refer to Figure 5 , Figure 6 It can be seen that the modulation transfer function of the optical system in Example 2 is above 35% at 250 line pairs / mm, and the root mean square size is within 0.0025mm. It can be seen that the system has a good correction effect on various aberrations and has good imaging quality.

[0050] Embodiment 3, specifically, taking the lens of Embodiment 3 as an example, the system parameters of the optical system are focal length f=9.0 mm, aperture number FNO=1.0, maximum field of view half angle HFOV=30°, and total length of the optical system TTL=155.3 mm.

[0051] like Figure 7As shown in FIG. 1 , the large aperture lens based on the DOE surface type is, in order of the optical path, a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with negative optical power, and a tenth lens with positive optical power. Among them, S1 is the object side of the first lens, S2 is the image side of the first lens, S3 is the object side of the second lens, S4 is the image side of the second lens, S5 is the object side of the third lens, S6 is the image side of the third lens, S7 is the object side of the fourth lens, S8 is the image side of the fourth lens, S9 is the object side of the fifth lens, S10 is the image side of the fifth lens, S11 is the object side of the sixth lens, S12 is the image side of the sixth lens, S13 is the object side of the seventh lens, S14 is the image side of the seventh lens, S15 is the object side of the eighth lens, S16 is the image side of the eighth lens, S17 is the object side of the ninth lens, S18 is the image side of the ninth lens, S19 is the object side of the tenth lens, S20 is the image side of the tenth lens, the dotted line between S12 and S13 is the aperture, and the dotted line on the right side of S20 is the image plane.

[0052] The curvature radius R, thickness d, refractive index Nd and Abbe number Vd of each surface of this optical system are shown in Table 3.

[0053] Table 3

[0054] surface Radius of curvature thickness Refractive Index Abbe number 1 281.54498 7.39364 1.75722 52.42 2 19.1898 9.53655 3 -22.50561 7.90905 1.64652 32.85 4 unlimited 3.27463 5 -58.76697 7.92372 1.9 26.2 6 -37.14729 1 7 -3493.18574 8.02968 1.72041 56.02 8 -57.56493 45.35263 9 65.23138 7.95775 1.501 77.46 10 -105.8378 1.00003 11 36.41812 6.5061 1.8883 22.79 12 23.78822 10.87783 Aperture 2.23868 13 40.51182 8.02401 1.65155 62.75 14 1030.45359 7.41577 15 DOE 5.41436 1.501 77.46 16 29.12218 1.00659 17 21.15416 4.87288 1.9 22.94 18 11.3321 2.20056 19 13.16286 7.31913 1.69997 58.02 20 282.85965 7.99987 Image plane unlimited

[0055] Among them, the radius of curvature in Table 3 is the radius of curvature of the object side or image side of the corresponding surface number at the optical axis. The first value in the "Thickness" parameter column of the lens is the thickness of the lens on the optical axis, and the second value is the distance from the image side of the lens to the next surface on the optical axis. The direction from the object side of the first lens to the image side of the last lens is assumed to be the positive direction of the optical axis. The units of the radius of curvature and thickness in Table 3 are both mm. And the refractive index in Table 3 is obtained at a reference wavelength of 0.5876um.

[0056] In Example 3, the front surface of the eighth lens adopts a DOE surface shape, and only the second-order term is selected for the DOE surface shape, and the second-order term coefficient is 80.7206925, the radius R value is 0.0560414702, and the radial coordinate ρ value is 0.5876. The use of the DOE surface shape greatly improves the imaging quality of the optical system, and at the same time, only the second-order term coefficient is used to reduce the processing difficulty of the lens.

[0057] See also Figure 8 , Figure 8 The modulation function analysis diagram of the optical system of Example 3 is shown, wherein: Figure 8The modulation function analysis diagram of the optical system of Example 3 at 250 line pairs / mm is shown, wherein the diffraction limits of the meridional field of view and the sagittal field of view coincide, and the diffraction transfer functions of the meridional field of view and the sagittal field of view of the 0 field of view coincide. Figure 8 In the figure, the horizontal axis along the X-axis represents the line pair value in mm, and the vertical axis along the Y-axis represents the modulation transfer function value; Figure 8 It can be seen from the figure that the modulation transfer function of the optical system in Example 3 is above 35% at 250 line pairs / mm, indicating that the imaging quality of the optical system in this example is good.

[0058] See also Fig. 9 , Fig. 9 is a diagram of the root mean square spot size of the full field of view of the optical system in Example 3, wherein the abscissa along the X-axis direction represents the relative field of view, and the ordinate along the Y-axis direction represents the root mean square size; Fig. 9 It can be seen that under the full field of view, the root mean square size of the optical system is within 0.0025 mm, indicating that the various aberrations of the optical system in this embodiment are well corrected.

[0059] Please refer to Figure 8 , Fig. 9 It can be seen that the modulation transfer function of the optical system in Example 3 is above 35% at 250 line pairs / mm, and the root mean square size is within 0.0025mm. It can be seen that the optical system in this embodiment has a good correction effect on various aberrations and has good imaging quality.

[0060] In summary, embodiments 1, 2, and 3 of the present invention application are a large aperture lens based on a DOE surface type. The optical system uses advanced diffractive optical elements as key components to optimize imaging performance by precisely controlling the light propagation path. Compared with traditional optical systems, DOE surface lenses can achieve a larger effective aperture while maintaining high image quality, ensuring high-definition imaging from the center to the edge. A large aperture lens with an F number of 1.0, a focal length of 9mm, and a half field of view of 30° was invented, which overcomes the problems of small half field of view angles and large F number values ​​of existing lenses, while also improving the corresponding imaging quality, achieving a modulation transfer function of more than 35% at 250 line pairs / mm.

Claims

1. A large aperture lens based on a DOE surface type, characterized in that: The focal length of the lens is 9 mm, the aperture F number is 1.0, and the modulation transfer function is above 35% at 250 line pairs. The lens includes, in order from the object side to the image side along the optical axis: a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with positive optical power, a sixth lens with negative optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with negative optical power, and a tenth lens with positive optical power; wherein the eighth lens is a meniscus lens with positive optical power, the front surface of which is described by a DOE surface type, and the rear surface is a spherical surface; The optical system of the lens satisfies the relationship: 15<(TTL / F) / FNUM<20, wherein F is the effective focal length of the optical system, TTL is the length of the optical system, and FNUM is the relative aperture of the optical system.

2. The large aperture lens based on the DOE surface type according to claim 1, characterized in that: The refractive index of the fifth lens is in the range of 1.5 to 1.8; the center thickness of the sixth lens is in the range of 6.5 to 8 mm, and the refractive index is in the range of 1.8 to 2.0; the center thickness of the seventh lens is in the range of 7 to 8.5 mm, and the refractive index is in the range of 1.6 to 1.8; the center thickness of the eighth lens is in the range of 5 to 6 mm, and the refractive index is in the range of 1.45 to 1.

55.

3. The large aperture lens based on DOE surface type according to claim 1, characterized in that: The half field angle w of the optical system of the lens is 30°.

4. The large aperture lens based on DOE surface type according to claim 1, characterized in that: The back focus BACK of the optical system satisfies the relationship: 7.9mm≦BACK≦8.3mm.

5. The large aperture lens based on DOE surface type according to claim 1, characterized in that: The eighth lens satisfies the relationship: 8.0≦|f / F|≦8.5, wherein f is the effective focal length of the eighth lens, and F is the effective focal length of the optical system.

6. The large aperture lens based on DOE surface type according to claim 1, characterized in that: The eighth lens satisfies the relationship: 2.3≦|d / H|≦2.8, wherein d is the aperture value of the eighth lens, and H is the thickness of the eighth lens.

Images