A fixed focus lens

Abstract

The application discloses a fixed focus lens, comprising: a first lens with negative refractive power, a second lens with negative refractive power, a third lens with negative refractive power, a diaphragm, a fourth lens with positive refractive power, a fifth lens with negative refractive power, a sixth lens with positive refractive power, a seventh lens with positive refractive power, and an eighth lens with negative refractive power arranged in sequence along an optical axis from an object side to an image side; wherein the fifth lens and the sixth lens are cemented; the first lens, the fourth lens, the fifth lens, and the sixth lens are all glass spherical lenses, and the second lens, the third lens, the seventh lens, and the eighth lens are all plastic aspherical lenses. The 4G4P combination can well correct aberration, reduce distortion, ensure good image quality, improve resolution, and the total optical length is less than or equal to 15 mm.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical lens, in particular to a fixed focus lens. BACKGROUND

[0002] With the continuous upgrading of Internet technology, the quality of fixed focus lenses is also increasingly pursued. In the fields of video conferencing, network video shooting, vehicle-mounted lenses or monitors, etc., fixed focus lenses with high clarity, good imaging quality, low distortion, short total length and low cost are needed.

[0003] However, the current fixed focus lens configuration is difficult to correct the system aberration well, and there are problems such as poor imaging quality and high distortion. In addition, the total optical length of the lens is generally greater than 24mm, which makes the volume of the lens too large, and the corresponding gasket size is also large, increasing the overall cost of the lens. SUMMARY

[0004] The present application provides a fixed focus lens, which adopts a 4G4P combination, can well correct aberration, reduce distortion, and at the same time ensure good enough image quality, improve resolution, and the total optical length is less than or equal to 15mm.

[0005] To achieve the above object, the embodiment of the present application provides a fixed focus lens, comprising: a first lens with negative focal power, a second lens with positive focal power, a third lens with negative focal power, or a second lens with negative focal power, a third lens with positive focal power, or a second lens with positive focal power, a third lens with positive focal power, and a diaphragm, a fourth lens with positive focal power, a fifth lens with negative focal power, a sixth lens with positive focal power, a seventh lens with positive focal power, and an eighth lens with negative focal power, arranged in order along the optical axis from the object side to the image side; wherein the fifth lens and the sixth lens are cemented; the first lens, the fourth lens, the fifth lens, the sixth lens are all glass spherical lenses, and the second lens, the third lens, the seventh lens and the eighth lens are all plastic aspherical lenses.

[0006] Optionally, in the direction of the optical axis from the object side to the image side, the object side surface of the first lens is a convex surface, and the image side surface is a concave surface; the object side surface of the second lens is a concave surface, and the image side surface is a convex surface; the object side surface of the third lens is a convex surface, and the image side surface is a concave surface; the object side surface of the fourth lens is a convex surface, and the image side surface is a convex surface; the object side surface of the fifth lens is a convex surface, and the image side surface is a concave surface; the object side surface of the sixth lens is a convex surface, and the image side surface is a convex surface; the object side surface of the seventh lens is a concave surface, and the image side surface is a convex surface; the object side surface of the eighth lens is a convex surface, and the image side surface is a concave surface.

[0007] Optionally, the refractive index N5 of the fifth lens and the refractive index N6 of the sixth lens satisfy the relationship: 0.05≤|N5-N6|≤0.20.

[0008] Optionally, the Abbe number V1 of the first lens, the Abbe number V2 of the second lens, the Abbe number V3 of the third lens, the Abbe number V4 of the fourth lens, the Abbe number V5 of the fifth lens, the Abbe number V6 of the sixth lens, the Abbe number V7 of the seventh lens, and the Abbe number V8 of the eighth lens satisfy the following relationships: V2+V3+V8≥70.000; |V3-V5|≥4.000; V4+V5+V6+V7≤230.000; V3+V5+V7≤150.000; V2+V3+V4+V5≤200.00; |V1-V8|≤50.000; |V2-V5|≤15.000; 20.0≤|V5-V6|≤40.0.

[0009] Optionally, the first lens to the eighth lens satisfy the following relationships: (T1+T8) / T3≥0.75; (T7+G78+T8) / (G45+T5+G67)≥0.9; (T1+G23) / (G12+G78)≥0.2; (T3+T6) / T8≤5.200; wherein T1 is the center thickness of the first lens; T3 is the center thickness of the third lens; T5 is the center thickness of the fifth lens; T6 is the center thickness of the sixth lens; T7 is the center thickness of the seventh lens; T8 is the center thickness of the eighth lens; G12 is the air gap between the first lens and the second lens; G23 is the air gap between the second lens and the third lens; G45 is the air gap between the fourth lens and the fifth lens; G67 is the air gap between the sixth lens and the seventh lens; G78 is the air gap between the seventh lens and the eighth lens.

[0010] Optionally, the first lens to the eighth lens satisfy the following relationships: (G45+G78+EFL) / (T3+T5)≥2.300; EFL / (G12+T2+G45)≥1.20; wherein T2 is the center thickness of the second lens; T3 is the center thickness of the third lens; T5 is the center thickness of the fifth lens; G12 is the air gap between the first lens and the second lens; G45 is the air gap between the fourth lens and the fifth lens; G78 is the air gap between the seventh lens and the eighth lens; EFL is the front focal length of the fixed focus lens.

[0011] Optionally, the first lens, the second lens, the seventh lens and the eighth lens satisfy the following relationship: ALT / (T1+G12)≤4.400; ALT / (G23+G78)≤90; wherein T1 is the center thickness of the first lens; G12 is the air gap between the first lens and the second lens; G23 is the air gap between the second lens and the third lens; G78 is the air gap between the seventh lens and the eighth lens; ALT is the sum of the center thicknesses of the lenses from the first lens to the eighth lens.

[0012] Optionally, the second lens to the fourth lens satisfy the following relationship: TL / (G23+T3+G34+T4)≥3.0; TL / (G23+G34+T4)≤5.300; wherein T3 is the center thickness of the third lens; T4 is the center thickness of the fourth lens; G23 is the air gap between the second lens and the third lens; G34 is the air gap between the third lens and the fourth lens; TL is the distance between the object side surface of the first lens and the image side surface of the eighth lens.

[0013] Optionally, the second lens to the eighth lens satisfy the following relationship: ALT / (T2+BFL)≥2.0; HFOV / (T6+T7+T8)≤10.00; TTL / (G34+G45+G78)≤25.00; AAG / (T3+G45)≤3.0; wherein T2 is the center thickness of the second lens; T3 is the center thickness of the third lens; T6 is the center thickness of the sixth lens; T7 is the center thickness of the seventh lens; T8 is the center thickness of the eighth lens; ALT is the sum of the center thicknesses of the lenses from the first lens to the eighth lens; AAG is the sum of the air gaps between the lenses from the first lens to the eighth lens; HFOV is half of the field angle corresponding to the diagonal image height; TTL is the total length of the fixed focus lens; BFL is the back focal length of the fixed focus lens; G34 is the air gap between the third lens and the fourth lens; G45 is the air gap between the fourth lens and the fifth lens; G78 is the air gap between the seventh lens and the eighth lens.

[0014] Optionally, the back focal length BFL of the fixed focus lens, the front focal length EFL of the fixed focus lens, and the aperture Fno of the fixed focus lens satisfy the following relationship: (EFL+BFL) / Fno≥3.50.

[0015] Optionally, the back focal length BFL of the fixed focus lens and the sum AAG of the air gaps between the lenses from the first lens to the eighth lens in the fixed focus lens satisfy the following relationship: AAG / BFL≥0.8.

[0016] Optionally, the back focal length BFL of the fixed focus lens, and the half image height ImgH of the fixed focus lens satisfy the following relationship: ImgH / BFL≥1.

[0017] Optionally, the total length TTL of the fixed focus lens, and the half field of view HFOV of the fixed focus lens satisfy the following relationship: HFOV / TTL≤2.2.

[0018] Optionally, the total length TTL of the fixed focus lens is less than or equal to 15.000mm.

[0019] The fixed focus lens provided by the embodiment of the present application comprises, in order along the optical axis from the object side to the image side, a first lens with negative refractive power, a second lens with positive refractive power, a third lens with negative refractive power, or a second lens with negative refractive power, a third lens with positive refractive power, or a second lens with positive refractive power, a third lens with positive refractive power, and a diaphragm, a fourth lens with positive refractive power, a fifth lens with negative refractive power, a sixth lens with positive refractive power, a seventh lens with positive refractive power, and an eighth lens with negative refractive power; wherein the fifth lens and the sixth lens are cemented; the first lens, the fourth lens, the fifth lens, and the sixth lens are all glass spherical lenses, and the second lens, the third lens, the seventh lens, and the eighth lens are all plastic aspherical lenses. The 4G4P combination can well correct aberration, reduce distortion, ensure good image quality, improve resolution, and the total optical length is less than or equal to 15mm.

[0020] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0022] Figure 1 is a structural schematic diagram of the fixed focus lens provided by the first embodiment of the present application;

[0023] Figure 2 is a structural schematic diagram of the fixed focus lens provided by the second embodiment of the present application;

[0024] Figure 3 is a structural schematic diagram of the fixed focus lens provided by the third embodiment of the present application;

[0025] Figure 4 is a spherical aberration curve of the fixed focal length lens of the embodiment of the present application;

[0026] Figure 5 is a field curvature distortion curve of the fixed focal length lens of the embodiment of the present application;

[0027] Figure 6 is a chromatic aberration curve of the fixed focal length lens of the embodiment of the present application;

[0028] Figure 7 is a spherical aberration curve of the fixed focal length lens of the embodiment of the present application;

[0029] Figure 8 is a field curvature distortion curve of the fixed focal length lens of the embodiment of the present application;

[0030] Figure 9 is a chromatic aberration curve of the fixed focal length lens of the embodiment of the present application;

[0031] Figure 10 is a spherical aberration curve of the fixed focal length lens of the embodiment of the present application;

[0032] Figure 11 is a field curvature distortion curve of the fixed focal length lens of the embodiment of the present application;

[0033] Figure 12 is a chromatic aberration curve of the fixed focal length lens of the embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to make the personnel in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0035] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0036] The fixed focus lens comprises, in order along the optical axis from the object side to the image side, a first lens with negative optical power, a second lens with positive optical power, a third lens with negative optical power, or a second lens with negative optical power, a third lens with positive optical power, or a second lens with positive optical power, a third lens with positive optical power, and a diaphragm, a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power; wherein the fifth lens and the sixth lens are cemented; the first lens, the fourth lens, the fifth lens, and the sixth lens are all glass spherical lenses, and the second lens, the third lens, the seventh lens, and the eighth lens are all plastic aspherical lenses.

[0037] It can be understood that the optical power is equal to the difference between the image beam convergence degree and the object beam convergence degree, and its value is the reciprocal of the focal length, which represents the ability of the optical system to deflect light. The greater the absolute value of the optical power, the stronger the bending ability of the light, and the smaller the absolute value of the optical power, the weaker the bending ability of the light. When the optical power is positive, the refraction of the light is convergent; when the optical power is negative, the refraction of the light is divergent. The optical power can be used to represent a certain refractive surface of a lens (i.e. a surface of the lens), a certain lens, or a system formed by multiple lenses.

[0038] By setting the first lens as a negative lens, the large field of view light can be as much as possible convergent into the system, which is beneficial to improve the field of view angle of the optical system, and the first lens adopts negative optical power and the rear-end structure to form a symmetrical optical system, which can reduce distortion. The fourth lens is set as a positive lens, which is located after the stop of the system, which is beneficial to correct chromatic aberration and improve the imaging quality of the optical system; at the same time, it can also gently transfer light, reduce the tolerance sensitivity of the optical system, and improve the assembly yield of the optical system. The fifth lens is set as a negative lens, and the sixth lens is set as a positive lens, which are cemented, which can effectively control the trend of light. The seventh lens is set as a negative lens, and the eighth lens is set as a negative lens, which is beneficial to shorten the total length of the optical system, and also allows the light to reach the image plane at a small angle.

[0039] The diaphragm is located between the third lens and the fourth lens, which can effectively converge the light entering the optical system, shorten the total length of the optical system, and effectively reduce the maximum aperture of the optical system. The use of 4G4P glass-plastic hybrid is beneficial to reduce the cost of the optical system, and is also beneficial to balance the high and low temperature performance of the optical lens, so that the optical lens has high imaging quality and good chromatic aberration in the range of-40℃ to 80℃.

[0040] Optionally, in the direction from the object side to the image side along the optical axis, the object side surface of the first lens is convex, the image side surface is concave; the object side surface of the second lens is concave, the image side surface is convex; the object side surface of the third lens is convex, the image side surface is concave; the object side surface of the fourth lens is convex, the image side surface is convex; the object side surface of the fifth lens is convex, the image side surface is concave; the object side surface of the sixth lens is convex, the image side surface is convex; the object side surface of the seventh lens is concave, the image side surface is convex; the object side surface of the eighth lens is convex, the image side surface is concave.

[0041] That is, the first lens is a convex-concave lens, the second lens is a concave-convex lens, the third lens is a convex-concave lens, the fourth lens is a convex-convex lens, the fifth lens is a convex-concave lens, the sixth lens is a convex-convex lens, the seventh lens is a concave-convex lens, and the eighth lens is a convex-concave lens, wherein the fifth lens and the sixth lens are cemented, which can better correct chromatic aberration and improve imaging quality on the one hand, and can better reduce the size of the lens and miniaturize the lens on the other hand.

[0042] Optionally, the refractive index N5 of the fifth lens and the refractive index N6 of the sixth lens satisfy the relationship: 0.05≤|N5-N6|≤0.20. Thus, the assembly yield can be improved, the air gap between the lenses can be reduced, and the design of the corresponding refractive index can correct various types of chromatic aberration and improve image quality.

[0043] Optionally, the Abbe number V1 of the first lens, the Abbe number V2 of the second lens, the Abbe number V3 of the third lens, the Abbe number V4 of the fourth lens, the Abbe number V5 of the fifth lens, the Abbe number V6 of the sixth lens, the Abbe number V7 of the seventh lens, and the Abbe number V8 of the eighth lens satisfy the following relationship: V2+V3+V8≥70.000; |V3-V5|≥4.000; V4+V5+V6+V7≤230.000; V3+V5+V7≤150.000; V2+V3+V4+V5≤200.00; |V1-V8|≤50.000; |V2-V5|≤15.000; 20.0≤|V5-V6|≤40.0. Thus, the corresponding Abbe number can correct various types of chromatic aberration and aberration, and improve image quality.

[0044] Optionally, the first lens to the eighth lens satisfy the following relationship: (T1+T8) / T3≥0.75; (T7+G78+T8) / (G45+T5+G67)≥0.9; (T1+G23) / (G12+G78)≥0.2; (T3+T6) / T8≤5.200; wherein, T1 is the center thickness of the first lens; T3 is the center thickness of the third lens; T5 is the center thickness of the fifth lens; T6 is the center thickness of the sixth lens; T7 is the center thickness of the seventh lens; T8 is the center thickness of the eighth lens; G12 is the air gap between the first lens and the second lens; G23 is the air gap between the second lens and the third lens; G45 is the air gap between the fourth lens and the fifth lens; G67 is the air gap between the sixth lens and the seventh lens; G78 is the air gap between the seventh lens and the eighth lens. Thus, the optical total length of the lens can be effectively reduced on the basis of reducing chromatic aberration and spherical aberration, which helps to improve the production yield and is conducive to reducing the sensitivity of the optical lens.

[0045] Optionally, the first lens to the eighth lens satisfy the following relationship: (G45+G78+EFL) / (T3+T5)≥2.300; EFL / (G12+T2+G45)≥1.20; wherein, T2 is the center thickness of the second lens; T3 is the center thickness of the third lens; T5 is the center thickness of the fifth lens; G12 is the air gap between the first lens and the second lens; G45 is the air gap between the fourth lens and the fifth lens; G78 is the air gap between the seventh lens and the eighth lens; EFL is the front focal length of the fixed focus lens. Thus, the optical total length of the lens can be effectively reduced on the basis of reducing chromatic aberration and spherical aberration, which helps to improve the production yield and is conducive to reducing the sensitivity of the optical lens.

[0046] Optionally, the first lens, the second lens, the seventh lens and the eighth lens satisfy the following relationship: ALT / (T1+G12)≤4.400; ALT / (G23+G78)≤90; wherein, T1 is the center thickness of the first lens; G12 is the air gap between the first lens and the second lens; G23 is the air gap between the second lens and the third lens; G78 is the air gap between the seventh lens and the eighth lens; ALT is the sum of the center thicknesses of the lenses in the first lens to the eighth lens. Thus, the optical total length of the lens can be effectively reduced on the basis of reducing chromatic aberration and spherical aberration, which helps to improve the production yield and is conducive to reducing the sensitivity of the optical lens.

[0047] Optionally, the second lens to the fourth lens satisfy the following relationship: TL / (G23+T3+G34+T4)≥3.0; TL / (G23+G34+T4)≤5.300; wherein, T3 is the center thickness of the third lens; T4 is the center thickness of the fourth lens; G23 is the air gap between the second lens and the third lens; G34 is the air gap between the third lens and the fourth lens; TL is the distance between the object side of the first lens and the image side of the eighth lens. Thus, the total optical length of the lens can be effectively reduced on the basis of reducing chromatic aberration and spherical aberration, which helps to improve the production yield and reduce the sensitivity of the optical lens.

[0048] Optionally, the second lens to the eighth lens satisfy the following relationship: ALT / (T2+BFL)≥2.0; HFOV / (T6+T7+T8)≤10.00; TTL / (G34+G45+G78)≤25.00; AAG / (T3+G45)≤3.0; wherein, T2 is the center thickness of the second lens; T3 is the center thickness of the third lens; T6 is the center thickness of the sixth lens; T7 is the center thickness of the seventh lens; T8 is the center thickness of the eighth lens; ALT is the sum of the center thicknesses of the lenses in the first lens to the eighth lens; AAG is the sum of the air gaps between the lenses in the first lens to the eighth lens; HFOV is half of the field of view angle corresponding to the diagonal image height; TTL is the total length of the fixed focus lens; BFL is the back focal length of the fixed focus lens; G34 is the air gap between the third lens and the fourth lens; G45 is the air gap between the fourth lens and the fifth lens; G78 is the air gap between the seventh lens and the eighth lens. Thus, the total optical length of the lens can be effectively reduced on the basis of reducing chromatic aberration and spherical aberration, which helps to improve the production yield and reduce the sensitivity of the optical lens.

[0049] Optionally, the back focal length BFL of the fixed focus lens, the front focal length EFL of the fixed focus lens, and the aperture Fno of the fixed focus lens satisfy the following relationship: (EFL+BFL) / Fno≥3.50. Thus, the entrance pupil diameter can be reasonably controlled, the assembly yield of the optical lens can be improved, and the installation space of elements such as gaskets can be reserved in advance.

[0050] Optionally, the back focal length BFL of the fixed focus lens and the sum AAG of the air gaps between the lenses in the first lens to the eighth lens in the fixed focus lens satisfy the following relationship: AAG / BFL≥0.8.

[0051] Optionally, the back focal length BFL of the fixed focus lens and the half image height ImgH of the fixed focus lens satisfy the following relationship: ImgH / BFL≥1. The total design length of the optical lens can be reduced, which is conducive to the miniaturization of the lens and facilitates the matching of 1 / 2.7 inch chips.

[0052] Optionally, the total length TTL of the fixed-focus lens and the half field of view HFOV of the fixed-focus lens satisfy the following relationship: HFOV / TTL≤2.2. The design total length of the optical lens can be reduced, which is beneficial to miniaturization of the lens and facilitates matching with a 1 / 2.7 inch chip.

[0053] Optionally, the total length TTL of the fixed-focus lens is less than or equal to 15.000 mm.

[0054] Therefore, the fixed-focus lens according to the embodiment of the present application comprises, in order along the optical axis from the object side to the image side, a first lens with negative refractive power, a second lens with positive refractive power, a third lens with negative refractive power, or a second lens with negative refractive power, a third lens with positive refractive power, or a second lens with positive refractive power, a third lens with positive refractive power, and a diaphragm, a fourth lens with positive refractive power, a fifth lens with negative refractive power, a sixth lens with positive refractive power, a seventh lens with positive refractive power, and an eighth lens with negative refractive power; wherein the fifth lens and the sixth lens are cemented; the first lens, the fourth lens, the fifth lens, and the sixth lens are all glass spherical lenses, and the second lens, the third lens, the seventh lens, and the eighth lens are all plastic aspherical lenses. The 4G4P combination is adopted, and the lenses cooperate with each other, so that the fixed-focus lens can meet the requirements of low distortion and high resolution, can well correct aberration, can maintain good imaging quality at a working distance, and can match a 1 / 2.7 inch chip. The total length of the lens is less than 15 mm, the aperture is less than or equal to 1.9, the focal length is about 5 mm, and the distortion is less than 0.1%.

[0055] The specific embodiments (Embodiment One to Embodiment Three) of the fixed-focus lens applicable to the above embodiments are further described below with reference to the accompanying drawings. The parameters of each embodiment meeting the above relationship are shown in Table 1:

[0056] Table 1: Parameters of each relationship of Embodiment One to Embodiment Three

[0057]

[0058]

[0059] In the embodiment of the present application, the aspherical conic coefficient of the fixed-focus lens can be limited by the following aspherical formula, but is not limited to the following representation method:

[0060]

[0061] Wherein: z is the distance from the vertex of the aspherical lens to the position of the aspherical lens along the optical axis direction at the height of y, c=1 / R, R represents the curvature radius of the center of the aspherical lens surface type, k represents the conic coefficient, and the parameters A, B, C, D and E are high-order aspherical coefficients.

[0062] In the embodiment one to the embodiment three, the fixed focus lens comprises a convex-concave first lens 1 with negative focal power, a concave-convex second lens 2, a convex-concave third lens 3, a convex-convex fourth lens 4 with positive focal power, a convex-concave fifth lens 5 with negative focal power, a convex-convex sixth lens 6 with positive focal power, a concave-convex seventh lens 7 with negative focal power, and a convex-concave eighth lens 8 with negative focal power. Figures 1 to 3 As shown in the figure, the fixed focus lens comprises a convex-concave first lens 1 with negative focal power, a concave-convex second lens 2, a convex-concave third lens 3, a convex-convex fourth lens 4 with positive focal power, a convex-concave fifth lens 5 with negative focal power, a convex-convex sixth lens 6 with positive focal power, a concave-convex seventh lens 7 with negative focal power, and a convex-concave eighth lens 8 with negative focal power. The fifth lens 5 and the sixth lens 6 are cemented together; the first lens 1, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are glass spherical lenses, and the second lens 2, the third lens 3, the seventh lens 7 and the eighth lens 8 are plastic aspherical lenses. The fixed focus lens further comprises a filter 9. An image plane IMA is located at a certain position on the side of the filter 9 away from the eighth lens 8.

[0063] Embodiment one

[0064] Figure 1 is a structural schematic diagram of the fixed focus lens according to the embodiment one of the present application. The fixed focus lens according to the embodiment one has a focal length f of 4.7091 mm, an F# of 1.9, and a total length of 14.0 mm, and the best working object distance of the system is infinity. The design values of the fixed focus lens are shown in Table 2.

[0065] Table 2: Design values of the fixed focus lens according to the embodiment one

[0066] Surface No. Surface Type Curvature Radius (mm) Thickness (mm) Refractive Index / Abbe Number (N / V) Half Apex S1 Sphere 4.9782 0.7545 1.59 / 68.6 2.6987 S2 Sphere 2.2641 1.6748 2.0000 S3 Asphere -3.0425 0.7320 1.64 / 23.5 1.9382 S4 Asphere -2.6794 0.0600 1.9639 S5 Asphere 7.4593 0.6000 1.64 / 23.5 1.8592 S6 Asphere 4.6183 0.2986 1.7421 STOP Standard Surface Infinity -0.0734 1.7370 S8 Sphere 5.6002 1.8555 1.59 / 68.6 1.8169 S9 Sphere -4.5863 0.2800 1.9000 S10 Sphere 22.2616 0.9701 1.74 / 28.3 1.9000 S11 Sphere 3.3471 1.7709 1.63 / 60.6 1.8883 S12 Sphere 233.8247 0.3449 1.9800 S13 Asphere -2.7645 0.7425 1.54 / 55.7 1.9978 S14 Asphere -1.8825 0.0550 2.0699 S15 Asphere 2.8895 0.6380 1.64 / 23.5 2.3628 S16 Asphere 1.7938 0.7441 2.5644 S17 Sphere Infinity 0.6000 H-K9L 2.6548 S18 Sphere Infinity 1.9556 2.7894 IMA Sphere Infinity 0.0000 3.4772

[0067] In Table 2, the surface numbers are numbered according to the surface order of the lenses, and “STO” represents the stop of the lens. The curvature radius represents the bending degree of the lens surface, and a positive value represents that the surface is bent towards the image plane side, and a negative value represents that the surface is bent towards the object plane side. “INF” represents that the surface is a plane, and the curvature radius is infinite. The thickness represents the center axis distance from the current surface to the next surface. The refractive index represents the deflection ability of the material between the current surface and the next surface. The space represents that the current position is air, and the refractive index is 1. S17 represents the filter.

[0068] Table 3: Aspherical surface type design values of the fixed focus lens according to the embodiment one

[0069]

[0070]

[0071] Figure 4 is a spherical aberration curve of the fixed focus lens of the embodiment of the present application, the vertical direction represents the normalized aperture, 0 represents on the optical axis, and the vertical direction top represents the maximum pupil radius (1.2392 mm); the horizontal direction represents the offset amount relative to the ideal focal point, with the unit of millimeter (mm). Different linear curves in the figure represent different wavelengths of system imaging, which are 436 nm, 487 nm, 546 nm, 587 nm to 656 nm from left to right. Figure 4 It can be seen that the axial aberration of different wavelengths (436 nm, 487 nm, 546 nm, 587 nm to 656 nm) is controlled within the range of (-0.2 mm, +0.2 mm), which shows that the spherical aberration of the fixed focus lens at each wavelength is well controlled, and can meet the wide spectrum application requirement.

[0072] In the following Figures 4 to 12 , the blue line represents 436 nm, the green line represents 487 nm, the red line represents 546 nm, the yellow line represents 587 nm, and the purple line represents 656 nm.

[0073] Figure 5 is a field curvature distortion curve of the fixed focus lens of the embodiment of the present application, in the left coordinate system in the figure, the horizontal coordinate represents the size of the field curvature, with the unit of mm; the vertical coordinate represents the normalized image height, without unit; wherein T represents the meridian, and S represents the sag (wherein, the maximum field of view is 37.713 degrees, the sagittal field curvature is 0.03 mm, and the meridian field curvature is 0.0338 mm); different linear curves in the figure represent different wavelengths of system imaging, which are 436 nm, 487 nm, 546 nm, 587 nm to 656 nm from left to right. Figure 5 It can be seen that the lens provided by the embodiment is effectively controlled in the field curvature from the wavelengths of 436 nm, 487 nm, 546 nm, 587 nm to 656 nm, that is, the difference between the central image quality and the peripheral image quality is small during imaging; in the right coordinate system, the horizontal coordinate represents the size of the distortion, with the unit of %; the vertical coordinate represents the normalized image height, without unit (wherein, the maximum field of view angle is 37.713 degrees, and the maximum distortion is 4.7312 %).

[0074] Figure 6 is a chromatic aberration curve of the fixed focus lens of the embodiment of the present application, the vertical direction represents the image height, with the unit of mm; the horizontal direction represents the offset amount of different wavelengths passing through the system at the image plane relative to the optical axis, with the unit of micrometer (μm). Different linear curves in the figure represent different wavelengths of system imaging (436 nm, 487 nm, 546 nm, 587 nm to 656 nm); the two vertical curves (i.e. the dotted line) in the figure are Airy disks.

[0075] Embodiment two

[0076] Figure 2is a structural schematic diagram of the fixed focus lens according to Embodiment Two of the present application. In Embodiment Two, the fixed focus lens has a focal length f of 4.4829 mm, an F# of 1.9, and a total length of 15.0 mm, and the optimal working distance of the system is infinity. The design values of the fixed focus lens are shown in Table 4.

[0077] Table 4 Design values of the fixed focus lens according to Embodiment Two

[0078] Surface No. Surface Type Curvature Radius (mm) Thickness (mm) Refractive Index / Abbe Number (N / V) Half Apex S1 Sphere 7.3791 0.5010 1.59 / 68.6 3.2227 S2 Sphere 3.0054 2.2164 2.5500 S3 Asphere -2.5936 0.7542 1.64 / 23.5 2.4639 S4 Asphere -2.8897 0.0519 2.3929 S5 Asphere 5.3750 1.4458 1.54 / 55.7 2.1774 S6 Asphere 6.1189 0.6944 1.8469 STOP Standard Surface Infinity -0.3223 1.7659 S8 Sphere 4.7477 1.9362 1.55 / 75.5 1.7700 S9 Sphere -5.4177 0.6153 1.9000 S10 Sphere 18.8861 0.5014 1.72 / 38.0 1.8650 S11 Sphere 2.3646 1.7786 1.61 / 60.6 1.7501 S12 Sphere -25.5051 0.4488 1.9900 S13 Asphere -2.6555 0.9856 1.54 / 55.7 1.8635 S14 Asphere -2.0411 0.0429 2.1198 S15 Asphere 3.3030 0.6267 1.67 / 19.3 2.4561 S16 Asphere 2.0088 0.7441 2.6732 S17 Sphere Infinity 0.6000 H-K9L 2.7732 S18 Sphere Infinity 1.3792 2.9300 IMA Sphere Infinity 0.0000 3.5019

[0079] In Table 4, the surface numbers are numbered according to the surface order of each lens, and "STO" represents the stop of the lens. The radius of curvature represents the bending degree of the lens surface, and a positive value represents that the surface is bent toward the image side, and a negative value represents that the surface is bent toward the object side. "INF" represents that the surface is a plane, and the radius of curvature is infinite. The thickness represents the center axis distance from the current surface to the next surface. The refractive index represents the light deflection ability of the material between the current surface and the next surface. The space represents that the current position is empty, and the refractive index is 1. S17 represents the filter.

[0080] Table 5 Aspheric surface type design values of the fixed focus lens according to Embodiment Two

[0081] Surface No. K A B C D E F S3 -4.05E+00 -1.82E-03 -4.76E-05 6.63E-05 -1.57E-05 6.18E-06 -5.18E-07 S4 -3.99E+00 -2.09E-03 -1.07E-04 8.33E-05 -5.67E-06 2.26E-06 -8.68E-08 S5 -1.21E+01 2.39E-04 1.44E-04 -1.44E-04 5.71E-05 -5.93E-06 3.24E-07 S6 -2.10E+01 2.42E-03 4.06E-04 -1.51E-04 5.47E-05 -8.43E-06 1.17E-06 S13 -3.65E+00 3.87E-03 3.87E-04 1.25E-04 -1.69E-06 -1.21E-05 5.62E-07 S14 -4.88E+00 -1.67E-03 2.87E-03 -4.62E-05 -1.22E-05 -1.93E-06 -6.65E-08 S15 -7.85E+00 -1.00E-02 6.08E-04 -1.17E-05 -4.05E-06 3.73E-07 -3.45E-08 S16 -6.92E+00 -7.22E-03 2.18E-04 2.07E-06 2.00E-07 -3.89E-07 2.54E-08

[0082] Figure 7 is a spherical aberration curve of the fixed focus lens according to Embodiment Two of the present application. The vertical direction represents the normalized aperture, and 0 represents the optical axis. The vertical direction represents the maximum pupil radius (1.1797 mm). The horizontal direction represents the relative ideal focus point offset, and the unit is millimeter (mm). Different line curves in the figure represent different wavelengths of system imaging, and the wavelengths are 436 nm, 487 nm, 546 nm, 587 nm to 656 nm. Figure 7 It can be seen that the axial aberration of different wavelengths (436 nm, 487 nm, 546 nm, 587 nm to 656 nm) is controlled within the range of (-0.2 mm, +0.2 mm), which indicates that the spherical aberration of the fixed focus lens at each wavelength is well controlled, and can meet the wide spectrum application requirement.

[0083] Figure 8 is a field curvature distortion curve of the fixed focus lens according to Embodiment Two of the present application. In the left coordinate system in the figure, the horizontal coordinate represents the size of the field curvature, and the unit is mm. The vertical coordinate represents the normalized image height, and has no unit. T represents the meridian, and S represents the sag (wherein, the maximum field of view is 37.713 degrees, the sagittal field curvature is 0.0363 mm, and the meridional field curvature is 0.1216 mm). Different line curves in the figure represent different wavelengths of system imaging, and the wavelengths are 436 nm, 487 nm, 546 nm, 587 nm to 656 nm. Figure 8It can be seen that the lens provided by the embodiment effectively controls the field curvature of light with wavelengths of 436 nm, 487 nm, 546 nm, 587 nm to 656 nm, that is, the difference between the central image quality and the peripheral image quality is small when imaging; in the right coordinate system, the horizontal coordinate represents the size of distortion, and the unit is %; the vertical coordinate represents the normalized image height, and there is no unit (wherein, the maximum field of view is 37.713 degrees, and the maximum distortion is 0.1079 %).

[0084] Figure 9 is a chromatic aberration curve of the fixed-focus lens of the embodiment two, the vertical direction represents the image height, and the unit is mm; the horizontal direction represents the offset of different wavelengths (436 nm, 487 nm, 546 nm, 587 nm to 656 nm) passing through the system at the image plane from the optical axis, and the unit is micrometers (μm). Different linear curves in the figure represent different wavelengths of the system imaging; the curves in the vertical direction on both sides of the figure are Airy disks.

[0085] Embodiment three

[0086] Figure 3 is a structural schematic diagram of the fixed-focus lens provided by the embodiment three. In the embodiment three, the focal length f of the fixed-focus lens is 4.5930 mm, the F# is 1.9, the total length is 14.9 mm, and the best working object distance of the system is infinity. The design values of the fixed-focus lens are shown in Table 6.

[0087] Table 6 Design values of the fixed-focus lens of the embodiment three

[0088] Surface No. Surface Type Curvature Radius (mm) Thickness (mm) Refractive Index / Abbe Number (N / V) Half Apex S1 Sphere 12.0546 0.5179 1.62 / 62.8 2.9711 S2 Sphere 3.4705 1.6811 2.4000 S3 Asphere -2.7301 1.0212 1.64 / 23.5 2.3630 S4 Asphere -2.7336 0.0601 2.3285 S5 Asphere 5.2056 1.2457 1.54 / 55.7 2.0658 S6 Asphere 4.8792 0.3688 1.7716 STOP Standard Surface Infinity -0.2823 1.7426 S8 Sphere 5.1946 2.3714 1.59 / 67.0 1.7462 S9 Sphere -5.8800 0.4611 1.7650 S10 Sphere 45.8468 0.9252 1.72 / 38.0 1.8650 S11 Sphere 2.1767 1.8488 1.62 / 63.4 1.8264 S12 Sphere -18.6864 0.2206 1.9900 S13 Asphere -3.7476 1.1006 1.54 / 55.7 1.9980 S14 Asphere -2.3226 0.0474 2.1960 S15 Asphere 3.9445 0.6447 1.54 / 55.7 2.6328 S16 Asphere 2.0679 0.7441 2.8504 S17 Sphere Infinity 0.6000 H-K9L 3.0034 S18 Sphere Infinity 1.2989 3.1155 IMA Sphere Infinity 0.0000 3.4917

[0089] In Table 6, the surface number is numbered according to the surface order of each lens, “STO” represents the diaphragm of the lens; the radius of curvature represents the bending degree of the lens surface, the positive value represents that the surface is bent to the image side, and the negative value represents that the surface is bent to the object side, wherein “INF” represents that the surface is a plane, and the radius of curvature is infinite; the thickness represents the central axis distance from the current surface to the next surface, the refractive index represents the deflection ability of the material between the current surface and the next surface to light, and the space represents that the current position is empty, and the refractive index is 1. S17 represents the filter.

[0090] Table 7 Aspheric surface type design values of the fixed-focus lens of the embodiment three

[0091] Surface No. K A B C D E F S3 -3.48E+00 -1.94E-04 2.56E-04 6.50E-05 -2.17E-05 5.66E-06 -5.19E-07 S4 -4.07E+00 -1.01E-03 3.25E-05 1.03E-04 -7.39E-06 1.88E-06 -2.52E-07 S5 -4.45E+00 1.33E-03 -9.24E-05 -1.97E-04 6.63E-05 -1.93E-06 -6.77E-07 S6 -2.01E+01 2.12E-03 3.16E-04 -1.70E-04 6.10E-05 -9.61E-06 8.62E-07 S13 -6.02E+00 6.94E-03 9.75E-04 1.24E-04 -1.81E-05 -1.53E-05 2.92E-06 S14 -7.74E+00 1.43E-03 3.17E-03 1.54E-06 -1.15E-05 -1.04E-06 4.46E-08 S15 -8.90E+00 -1.03E-02 6.41E-04 3.20E-06 -3.76E-06 6.21E-07 -1.15E-08 S16 -8.26E+00 -8.99E-03 1.46E-04 -7.22E-06 -1.99E-08 -3.33E-07 2.05E-08

[0092] Figure 10is a spherical aberration curve of the fixed focus lens of the third embodiment of the present application, the vertical direction represents the normalized aperture, 0 represents on the optical axis, and the vertical direction top represents the maximum pupil radius (1.2087mm); the horizontal direction represents the offset amount relative to the ideal focus point, with the unit of millimeter (mm). Different linear curves in the figure represent different wavelengths of system imaging, and the wavelengths are 436nm, 487nm, 546nm, 587nm to 656nm. Figure 10 It can be seen that the axial aberration of different wavelengths (436nm, 487nm, 546nm, 587nm to 656nm) is controlled within the range of (-0.2mm, +0.2mm), which shows that the spherical aberration of the fixed focus lens at each wavelength is well controlled, and can meet the wide spectrum application requirement.

[0093] Figure 11 is a field curvature distortion curve of the fixed focus lens of the third embodiment of the present application, in the left coordinate system in the figure, the horizontal coordinate represents the size of the field curvature, with the unit of mm; the vertical coordinate represents the normalized image height, without unit; wherein T represents the meridian, and S represents the sag (wherein, the maximum field of view is 37.713 degrees, the sagittal field curvature is 0.0157mm, and the meridian field curvature is 0.0699mm); and the right coordinate system in the figure is a distortion curve of the fixed focus lens of the third embodiment of the present application, wherein the horizontal coordinate represents the size of the distortion, with the unit of %; the vertical coordinate represents the normalized image height, without unit (wherein, the maximum field of view angle is 37.713 degrees, and the maximum distortion is 2.1436%). Figure 8 It can be seen that the lens provided in the embodiment is effectively controlled in the field curvature from the wavelengths of 436nm, 487nm, 546nm, 587nm to 656nm light, that is, the difference between the central image quality and the peripheral image quality is small during imaging; in the right coordinate system, the horizontal coordinate represents the size of the distortion, with the unit of %; the vertical coordinate represents the normalized image height, without unit (wherein, the maximum field of view angle is 37.713 degrees, and the maximum distortion is 2.1436%).

[0094] Figure 12 is a chromatic aberration curve of the fixed focus lens of the third embodiment of the present application, the vertical direction represents the image height, with the unit of mm; the horizontal direction represents the offset amount of different wavelengths (436nm, 487nm, 546nm, 587nm to 656nm) through the system at the image plane relative to the optical axis, with the unit of micrometer (μm). Different linear curves in the figure represent different wavelengths of system imaging; the vertical curves on both sides of the figure are Airy disks.

[0095] It should be understood that the various forms of flow shown above can be reordered, added or deleted steps. For example, each step described in the present application can be executed in parallel, sequentially or in different order, as long as the desired results of the technical solutions of the present application can be achieved, which is not limited herein.

[0096] The above detailed description does not limit the scope of the application. Various modifications, combinations, sub-combinations and alternatives can be made to the detailed description. Any modification, equivalent replacement and improvement etc. made within the spirit and principle of the application shall be included in the scope of the application.

Claims

1. A fixed-focus lens, characterized in that, include: Along the optical axis from the object side to the image side, the following lenses are arranged in sequence: a first lens with negative optical power, a second lens with positive optical power, a third lens with negative optical power, an aperture, a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power. The fifth lens and the sixth lens are cemented together; the first lens, the fourth lens, the fifth lens, and the sixth lens are all glass spherical mirrors, and the second lens, the third lens, the seventh lens, and the eighth lens are all plastic aspherical mirrors. The fixed-focus lens has eight lenses with optical power.

2. The fixed-focus lens according to claim 1, characterized in that, The back focal length BFL and the half-image height ImgH of the fixed-focus lens satisfy the following relationship: ImgH / BFL=1.

3. The fixed-focus lens according to claim 1, characterized in that, The back focal length BFL, front focal length EFL, and aperture Fno of the fixed-focus lens satisfy the following relationship: (EFL+BFL) / Fno=4.21510.

4. The fixed-focus lens according to claim 1, characterized in that, The total length (TTL) of the fixed-focus lens and the half field of view (HFOV) of the fixed-focus lens satisfy the following relationship: HFOV / TTL = 2.15410.

5. The fixed-focus lens according to claim 1, characterized in that, The half field of view HFOV of the fixed-focus lens, the center thickness T6 of the sixth lens, the center thickness T7 of the seventh lens, and the center thickness T8 of the eighth lens satisfy the following relationship: HFOV / (T6+T7+T8)=9.57200.

6. A fixed-focus lens, characterized in that, include: The first lens with negative optical power, the second lens with negative optical power, the third lens with positive optical power, the aperture stop, the fourth lens with positive optical power, the fifth lens with negative optical power, the sixth lens with positive optical power, the seventh lens with positive optical power, and the eighth lens with negative optical power. The fifth lens and the sixth lens are cemented together; the first lens, the fourth lens, the fifth lens, and the sixth lens are all glass spherical mirrors, and the second lens, the third lens, the seventh lens, and the eighth lens are all plastic aspherical mirrors. The fixed-focus lens has eight lenses with optical power.

7. The fixed-focus lens according to claim 6, characterized in that, The back focal length BFL and the half-image height ImgH of the fixed-focus lens satisfy the following relationship: ImgH / BFL=1.21180.

8. The fixed-focus lens according to claim 6, characterized in that, The back focal length BFL, front focal length EFL, and aperture Fno of the fixed-focus lens satisfy the following relationship: (EFL+BFL) / Fno=3.79270.

9. The fixed-focus lens according to claim 6, characterized in that, The total length (TTL) of the fixed-focus lens and the half field of view (HFOV) of the fixed-focus lens satisfy the following relationship: HFOV / TTL = 2.01100.

10. The fixed-focus lens according to claim 6, characterized in that, The half field of view HFOV of the fixed-focus lens, the center thickness T6 of the sixth lens, the center thickness T7 of the seventh lens, and the center thickness T8 of the eighth lens satisfy the following relationship: HFOV / (T6+T7+T8)=8.89570.

11. A fixed-focus lens, characterized in that, include: The first lens with negative optical power, the second lens with positive optical power, the third lens with positive optical power, the aperture, the fourth lens with positive optical power, the fifth lens with negative optical power, the sixth lens with positive optical power, the seventh lens with positive optical power, and the eighth lens with negative optical power. The fifth lens and the sixth lens are cemented together; the first lens, the fourth lens, the fifth lens, and the sixth lens are all glass spherical mirrors, and the second lens, the third lens, the seventh lens, and the eighth lens are all plastic aspherical mirrors. The fixed-focus lens has eight lenses with optical power.

12. The fixed-focus lens according to claim 11, characterized in that, The back focal length BFL and the half-image height ImgH of the fixed-focus lens satisfy the following relationship: ImgH / BFL=1.24870.

13. The fixed-focus lens according to claim 11, characterized in that, The back focal length BFL, front focal length EFL, and aperture Fno of the fixed-focus lens satisfy the following relationship: (EFL+BFL) / Fno=3.80840.

14. The fixed-focus lens according to claim 11, characterized in that, The total length (TTL) of the fixed-focus lens and the half field of view (HFOV) of the fixed-focus lens satisfy the following relationship: HFOV / TTL = 2.02780.

15. The fixed-focus lens according to claim 11, characterized in that, The half field of view HFOV of the fixed-focus lens, the center thickness T6 of the sixth lens, the center thickness T7 of the seventh lens, and the center thickness T8 of the eighth lens satisfy the following relationship: HFOV / (T6+T7+T8)=8.39280.

Images