Optical lens

Abstract

The application discloses an optical lens, which comprises, in sequence from an object side to an imaging surface along an optical axis, a first lens with positive focal power, the object side of which is a convex surface and the image side of which is a concave surface; a second lens with negative focal power, the object side of which is a convex surface and the image side of which is a concave surface; a third lens with positive focal power, the image side of which is a convex surface; a diaphragm; a fourth lens with positive focal power, the object side of which is a convex surface and the image side of which is a convex surface; a fifth lens with negative focal power; and a sixth lens with negative focal power, the object side of which is a convex surface near the optical axis and the image side of which is a concave surface near the optical axis; wherein the maximum field of view FOV of the optical lens and the aperture number FNO of the optical lens satisfy 30°<FOV / FNO<50°. The optical lens provided by the application has the advantages of large aperture, high pixels and the like.

Description

Technical Field

[0001] This invention relates to the field of imaging lens technology, and in particular to an optical lens. Background Technology

[0002] In recent years, with the continuous development of drone technology, the application fields of drone camera lenses have also been expanding. Besides traditional military reconnaissance and surveillance, drone camera lenses are now widely used in agriculture, environmental protection, construction, media, and other fields. Simultaneously, as consumer demand for drone photography continues to increase, drone camera lens technology is constantly being upgraded to meet the needs of different users. Due to the limited payload capacity of drones, lightweight lenses are needed to reduce the burden on the drone; high-resolution lenses can capture more details to meet the needs of different fields; and large-aperture lenses can increase the amount of light entering the camera, thereby improving the shooting effect. Summary of the Invention

[0003] Therefore, the purpose of this invention is to provide an optical lens that has at least the advantages of a large aperture and high pixel count.

[0004] This invention discloses an optical lens, comprising, along the optical axis from the object side to the imaging plane, the following components in sequence: a first lens with positive optical power, having a convex object side and a concave image side; a second lens with negative optical power, having a convex object side and a concave image side; a third lens with positive optical power, having a convex image side; an aperture stop; a fourth lens with positive optical power, having a convex object side and a convex image side; a fifth lens with negative optical power; and a sixth lens with negative optical power, having a convex object side near the optical axis and a concave image side near the optical axis; wherein the maximum field of view (FOV) of the optical lens and the aperture number (FNO) of the optical lens satisfy the following condition: 30° < FOV / FNO < 50°.

[0005] Compared with the prior art, the beneficial effects of the present invention are as follows: The optical lens provided by the present invention adopts six lenses. By reasonably allocating the optical power of each lens and reasonably adjusting the surface shape of each lens, while reasonably setting the thickness of each lens and the spacing between each lens, and placing the aperture stop between the third and fourth lenses, the optical lens can have at least the advantages of large field of view, large aperture, high image quality and low weight, which can meet the needs of UAVs. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the structure of the optical lens according to the first embodiment of the present invention.

[0007] Figure 2 This is a distortion curve diagram of the optical lens according to the first embodiment of the present invention.

[0008] Figure 3 This is an MTF curve of the optical lens according to the first embodiment of the present invention.

[0009] Figure 4 This is a chromatic aberration curve of the optical lens according to the first embodiment of the present invention.

[0010] Figure 5 This is a schematic diagram of the structure of the optical lens according to the second embodiment of the present invention.

[0011] Figure 6 This is a distortion curve diagram of the optical lens according to the second embodiment of the present invention.

[0012] Figure 7 This is an MTF curve of the optical lens according to the second embodiment of the present invention.

[0013] Figure 8 This is a chromatic aberration curve of the optical lens according to the second embodiment of the present invention.

[0014] Figure 9 This is a schematic diagram of the structure of the optical lens according to the third embodiment of the present invention.

[0015] Figure 10 This is a distortion curve diagram of the optical lens according to the third embodiment of the present invention.

[0016] Figure 11 This is an MTF curve of the optical lens according to the third embodiment of the present invention.

[0017] Figure 12 This is a chromatic aberration curve of the optical lens according to the third embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Throughout this specification, the same reference numerals refer to the same elements.

[0020] The present invention provides an optical lens, which includes, along the optical axis from the object side to the imaging plane, a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, and a filter, wherein the optical centers of each lens are located on the same straight line.

[0021] The first lens has positive optical power, its object-side surface is convex, and its image-side surface is concave. The second lens has negative optical power, its object-side surface is convex, and its image-side surface is concave. The third lens has positive optical power, its object-side surface is either convex or concave, and its image-side surface is convex. The fourth lens has positive optical power, its object-side surface is convex, and its image-side surface is convex. The fifth lens has negative optical power, its object-side surface is concave, and its image-side surface is convex near the optical axis. The sixth lens has negative optical power, its object-side surface is convex near the optical axis, and its image-side surface is concave near the optical axis.

[0022] In some implementations, the maximum field of view (FOV) of the optical lens and the aperture number (FNO) of the optical lens satisfy the condition: 30° < FOV / FNO < 50°. Meeting this condition helps to expand the field of view and increase the aperture of the optical lens, achieving wide-angle and large-aperture characteristics. The wide-angle characteristic allows the optical lens to acquire more scene information, meeting the needs of large-area detection, while the large aperture characteristic helps to mitigate the problem of rapid brightness decrease at the edges of the field of view caused by the wide-angle feature, thus also facilitating the acquisition of more scene information.

[0023] In some implementations, the image height IH corresponding to the maximum field of view of the optical lens and the total optical length TTL of the optical lens satisfy the condition: 0.4 < IH / TTL < 0.5. Satisfying the above condition helps to balance the total length of the optical lens and the image quality.

[0024] In some embodiments, the effective focal length f1 of the first lens and the effective focal length f of the optical lens satisfy the condition: 2.0 < f1 / f < 5.0. Satisfying the above condition allows the first lens to have an appropriate positive optical power, which helps to make the change in the refraction angle of the incident light more gradual, avoids excessive refraction changes that would produce too many aberrations, and at the same time helps more light to enter the rear lens, improving the relative illumination of the optical lens.

[0025] In some embodiments, the effective focal length f1 of the first lens and the effective focal length f2 of the second lens satisfy the condition: -3.5 < f1 / f2 < -2.0. Satisfying the above condition allows for a reasonable allocation of the focal lengths of the first and second lenses, which is beneficial for a smooth transition of light entering the optical system and can correct higher-order aberrations caused by excessive refraction of light by the first lens.

[0026] In some embodiments, the effective focal length f4 of the fourth lens and the effective focal length f1 of the first lens satisfy the following condition: 0.2 < f4 / f1 < 0.3; the center thickness CT4 of the fourth lens and the center thickness CT1 of the first lens satisfy the following condition: 1.5 < CT4 / CT1 < 2.0. Satisfying these conditions allows for a reasonable allocation of the focal length and thickness of the fourth and first lenses, which helps reduce the difficulty of aberration correction in the central and peripheral fields of view of the optical lens. Simultaneously, it enables the optical lens to have less distortion and improves the imaging quality.

[0027] In some embodiments, the combined focal length f45 of the fourth and fifth lenses and the effective focal length f of the optical lens satisfy: 1.0 < f45 / f < 2.1; the center thickness CT4 of the fourth lens, the center thickness CT5 of the fifth lens, the edge thickness ET4 of the fourth lens, and the edge thickness ET5 of the fifth lens satisfy: 1.2 < (CT4 + CT5) / (ET4 + ET5) < 1.4. Satisfying these conditions allows for a reasonable allocation of the focal length and thickness of the fourth and fifth lenses, resulting in a compact optical lens structure, smooth light entry, and improved illumination of the optical lens.

[0028] In some embodiments, the radius of curvature R62 of the image-side surface of the sixth lens and the effective focal length f of the optical lens satisfy the following condition: 0 < R62 / f < 1.0; the center thickness CT6 of the sixth lens and the total optical length TTL of the optical lens satisfy the following condition: 0.02 < CT6 / TTL < 0.03. By satisfying the above conditions and reasonably controlling the thickness and surface shape of the sixth lens, it is possible to increase the imaging area of ​​the optical lens while ensuring the machinability of the sixth lens, and at the same time, to ensure the resolving power of the optical lens.

[0029] In some embodiments, the center thickness CT1 of the first lens, the center thickness CT2 of the second lens, the center thickness CT3 of the third lens, the air gap AT12 between the first and second lenses on the optical axis, and the air gap AT23 between the second and third lenses on the optical axis satisfy the condition: 0.5 < (CT1 + CT2 + CT3) / (AT12 + AT23) < 1.0. By satisfying this condition and appropriately adjusting the thickness of each lens in the front lens group and the air gap between them, the light entering the front lens group can smoothly transition and converge at the aperture stop. This also helps to reduce aberrations and distortions in the optical lens, thereby improving the imaging quality of the optical lens.

[0030] In some embodiments, the radius of curvature R52 of the image-side surface of the fifth lens and the radius of curvature R61 of the object-side surface of the sixth lens satisfy: -1.5 < R52 / R61 < -0.5; the effective aperture D52 of the image-side surface of the fifth lens and the effective aperture D61 of the object-side surface of the sixth lens satisfy: 0.9 < D52 / D61 < 1.1. By satisfying these conditions and appropriately adjusting the surface shapes of the image-side surface of the fifth lens and the object-side surface of the sixth lens, a good light-gathering effect can be achieved, ensuring that the optical lens has a sufficient field of view while maximizing light transmission.

[0031] In some implementations, the optical back focal length (BFL) of the optical lens and the effective focal length (f) of the optical lens satisfy the condition: 0.23 < BFL / f < 0.45. Satisfying this condition allows the optical lens to have a longer optical back focal length, which is beneficial for the assembly of the optical lens.

[0032] In some embodiments, the radius of curvature R11 of the object-side surface of the first lens and the radius of curvature R22 of the image-side surface of the second lens satisfy: 3.0 < R11 / R22 < 6.0; the radius of curvature R12 of the image-side surface of the first lens and the radius of curvature R21 of the object-side surface of the second lens satisfy: 2.5 < R12 / R21 < 6.0. By satisfying these conditions and appropriately adjusting the surface shapes of the first and second lenses, it is beneficial to ensure a smooth transition of light entering the optical system, reduce higher-order aberrations of the optical lens, and improve the imaging quality of the optical lens.

[0033] As one implementation method, the optical lens provided by this invention can use all-plastic lenses or a hybrid glass-plastic combination, both of which can achieve good imaging results. In this embodiment, the optical lens uses a hybrid glass-plastic combination. By rationally allocating the optical power of each lens and optimizing the aspherical shape, the optical lens possesses advantages such as good imaging quality, a large field of view, a large image plane, a large aperture, and low weight. Specifically, the first and third lenses use glass spherical lenses, while the second, fourth, fifth, and sixth lenses use plastic aspherical lenses. By using a hybrid glass-plastic combination, the optical lens can have good thermal stability in both high and low temperature environments. At the same time, by using aspherical lenses, lens aberrations can be effectively corrected, imaging quality can be improved, and a more cost-effective optical performance product can be provided.

[0034] The present invention will be further described below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are different; for specific differences, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

[0035] In various embodiments of the present invention, when the lens in the optical lens is an aspherical lens, the aspherical surface shape of the lens satisfies the following equation: Where z represents the distance vector from the aspherical surface to the vertex along the optical axis at a height of h, c is the paraxial curvature of the surface, k is the quadratic surface coefficient, and A 2i is the aspherical surface shape coefficient of the 2ith order.

[0036] First Embodiment

[0037] Please see Figure 1 The diagram shown is a schematic diagram of the structure of an optical lens 100 provided in the first embodiment of the present invention. The optical lens 100 includes, along the optical axis from the object side to the imaging surface S15, the following components in sequence: a first lens L1, a second lens L2, a third lens L3, an aperture ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a filter G1.

[0038] Specifically, the first lens L1 has positive optical power, its object-side surface S1 is convex, and its image-side surface S2 is concave; the second lens L2 has negative optical power, its object-side surface S3 is convex, and its image-side surface S4 is concave; the third lens L3 has positive optical power, its object-side surface S5 is convex, and its image-side surface S6 is convex; the fourth lens L4 has positive optical power, its object-side surface S7 is convex, and its image-side surface S8 is convex; the fifth lens L5 has negative optical power, its object-side surface S9 is concave, and its image-side surface S10 is convex near the optical axis; the sixth lens L6 has negative optical power, its object-side surface S12 is convex near the optical axis, and its image-side surface S13 is concave near the optical axis; the filter G1 has an object-side surface S13 and an image-side surface S14. Among them, the second lens L2, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are all plastic aspherical lenses, while the first lens L1 and the third lens L3 are glass spherical lenses.

[0039] The relevant parameters of each lens in the optical lens 100 provided in this embodiment are shown in Table 1.

[0040] Table 1

[0041]

[0042] In this embodiment, the aspherical surface profile system of each lens in the optical lens 100 is shown in Table 2.

[0043] Table 2

[0044]

[0045] Please refer to Figure 2 , Figure 3 as well as Figure 4 The figures shown are the distortion curve, MTF curve, and lateral chromatic aberration curve of the optical lens 100, respectively. Among them, from... Figure 2 As can be seen, the distortion value is controlled within -8.0%, indicating that the distortion correction of the optical lens 100 is good; from Figure 3 As can be seen, the MTF value is above 0.6 throughout the entire field of view. Within the range of 0–30 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good image quality and detail resolution at both low and high frequencies. Figure 4 As can be seen, the chromatic aberration between the longest and shortest wavelengths is controlled within ±6.0μm, indicating that the chromatic aberration of the optical lens 100 is well corrected.

[0046] Second Embodiment

[0047] Please see Figure 5 The figure shown is a schematic diagram of the structure of the optical lens 200 provided in the second embodiment of the present invention. The structure of the optical lens 200 in this embodiment is basically the same as that of the optical lens 100 in the first embodiment. The difference is that the radius of curvature, aspherical coefficient and thickness of each lens surface are different.

[0048] Specifically, the relevant parameters of each lens in the optical lens 200 provided in this embodiment are shown in Table 3.

[0049] Table 3

[0050]

[0051] In this embodiment, the aspherical surface coefficients of each lens in the optical lens 200 are shown in Table 4.

[0052] Table 4

[0053]

[0054]

[0055] Please refer to Figure 6 , Figure 7 as well as Figure 8 The figures shown are the distortion curve, MTF curve, and transverse chromatic aberration curve of the optical lens 200, respectively. Among them, from... Figure 6 As can be seen, the distortion value is controlled within -7.0%, indicating that the distortion correction of the optical lens 200 is good; from Figure 7As can be seen, the MTF value is above 0.75 throughout the entire field of view. Within the range of 0–30 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good image quality and detail resolution at both low and high frequencies. Figure 8 As can be seen, the transverse chromatic difference between the longest and shortest wavelengths is controlled within ±6.0μm, indicating that the transverse chromatic difference of the optical lens 200 is well corrected.

[0056] Third Embodiment

[0057] Please see Figure 9 The figure shown is a schematic diagram of the structure of the optical lens 300 provided in the third embodiment of the present invention. The structure of the optical lens 300 in this embodiment is roughly the same as that of the optical lens 100 in the first embodiment. The main difference is that the curvature radius, aspherical coefficient and thickness of each lens surface are different.

[0058] Specifically, the relevant parameters of each lens in the optical lens 300 provided in this embodiment are shown in Table 5.

[0059] Table 5

[0060]

[0061] In this embodiment, the aspherical surface coefficients of each lens in the optical lens 300 are shown in Table 6.

[0062] Table 6

[0063]

[0064]

[0065] Please refer to Figure 10 , Figure 11 as well as Figure 12 The figures shown are the distortion curve, MTF curve, and transverse chromatic aberration curve of the optical lens 300, respectively. Among them, from... Figure 10 As can be seen, the distortion value is controlled within -7.0%, indicating that the distortion correction of the 300mm optical lens is good; from Figure 11 As can be seen, the MTF value is above 0.75 throughout the entire field of view. Within the range of 0–30 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good image quality and detail resolution at both low and high frequencies. Figure 12 As can be seen, the transverse chromatic difference between the longest and shortest wavelengths is controlled within ±4.5μm, indicating that the transverse chromatic difference of the optical lens 300 is well corrected.

[0066] Table 7 shows the optical characteristics of the optical lenses in the three embodiments above, mainly including the effective focal length f, aperture number FNO, total optical length TTL, maximum field of view FOV, image height IH corresponding to the maximum field of view, and the values ​​corresponding to each of the above conditions.

[0067] Table 7

[0068] First Embodiment Second Embodiment Third Embodiment f(mm) 17.692 17.700 17.711 FNO 1.300 1.300 1.300 TTL(mm) 40.009 40.000 40.009 IH(mm) 18.31 18.32 18.32 FOV (°) 58 58 58 FOV / FNO(°) 44.62 44.62 44.62 IH / TTL 0.458 0.458 0.458 f1 / f 3.490 3.760 3.414 f1 / f2 -3.065 -3.017 -2.581 f4 / f1 0.245 0.223 0.233 CT4 / CT1 1.810 1.655 1.773 f45 / f 2.066 1.637 1.116 (CT4+CT5) / (ET4+ET5) 1.335 1.274 1.304 R62 / f 0.657 0.687 0.564 CT6 / TTL 0.025 0.025 0.026 (CT1+CT2+CT3) / (AT12+AT23) 0.973 0.608 0.854 R52 / R61 -0.988 -0.792 -1.074 D52 / D61 0.993 0.993 0.970 BFL / f 0.437 0.247 0.299 R11 / R22 5.612 4.413 3.611 R12 / R21 5.553 3.763 3.002

[0069] In summary, the optical lens provided by the embodiments of the present invention has at least the following advantages:

[0070] (1) The optical glass provided in the embodiments of the present invention, by adopting a glass-plastic hybrid structure, not only enables the optical lens to have good thermal stability in high and low temperature environments, but also improves the imaging quality of the optical lens while reducing the weight of the optical lens.

[0071] (2) The optical glass provided in the embodiments of the present invention can achieve an aperture number (FNO) of 1.3, thus realizing the characteristics of a large aperture.

[0072] (3) The optical glass provided in the embodiments of the present invention can achieve a balance between large aperture, large image plane and high imaging quality under the condition of a large field of view.

[0073] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0074] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. An optical lens, six pieces of lenses in total, characterized in that, In order from the object side to the imaging plane along the optical axis, comprises successively: a first lens with positive refractive power, the object side surface of the first lens is convex, the image side surface of the first lens is concave; a second lens with negative refractive power, the object side surface of the second lens is convex, the image side surface of the second lens is concave; a third lens with positive refractive power, the image side surface of the third lens is convex; a diaphragm; a fourth lens with positive refractive power, the object side surface of the fourth lens is convex, the image side surface of the fourth lens is convex; a fifth lens with negative refractive power; a sixth lens with negative refractive power, the object side surface of the sixth lens is convex at the near optical axis, the image side surface of the sixth lens is concave at the near optical axis; Wherein, the maximum field angle FOV of the optical lens and the aperture number FNO of the optical lens satisfy: 30°<FOV / FNO<50°; The combined focal length f45 of the fourth lens and the fifth lens and the effective focal length f of the optical lens satisfy: 1.0<f45 / f<2.

1.

2. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: the image height IH corresponding to the maximum field angle of the optical lens and the total optical length TTL of the optical lens satisfy: 0.4<IH / TTL<0.

5.

3. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: the effective focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 2.0<f1 / f<5.

0.

4. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: the effective focal length f1 of the first lens and the effective focal length f2 of the second lens satisfy: -3.5<f1 / f2<-2.

0.

5. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: the effective focal length f4 of the fourth lens and the effective focal length f1 of the first lens satisfy: 0.2<f4 / f1<0.

3.

6. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: the maximum field angle FOV of the optical lens and the aperture number FNO of the optical lens satisfy: FOV / FNO=44.62°; The combined focal length f45 of the fourth lens and the fifth lens and the effective focal length f of the optical lens satisfy: 1.116≤f45 / f≤2.

066.

7. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: the radius of curvature R62 of the image side surface of the sixth lens and the effective focal length f of the optical lens satisfy: 0<R62 / f<1.

0.

8. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: the center thickness CT1 of the first lens, the center thickness CT2 of the second lens, the center thickness CT3 of the third lens, the air gap AT12 of the first lens and the second lens on the optical axis, and the air gap AT23 of the second lens and the third lens on the optical axis satisfy: 0.5<(CT1+CT2+CT3) / (AT12+AT23)<1.

0.

9. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: the radius of curvature R52 of the image side surface of the fifth lens and the radius of curvature R61 of the object side surface of the sixth lens satisfy: -1.5<R52 / R61<-0.

5.

10. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: an optical back focal length BFL of the optical lens and an effective focal length f of the optical lens satisfy: 0.23 < BFL / f < 0.

45. The optical lens satisfies the following conditional expression: an optical back focal length BFL of the optical lens and an effective focal length f of the optical lens satisfy: 0.23 < BFL / f < 0.45.

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