Aerial optical system and camera module for its application

Abstract

The embodiment of the application discloses a kind of aerial photography optical systems, successively include: first lens, second lens, third lens, fourth lens from object side to imaging surface side along optical axis;The object side surface of first lens is convex, and its optical power is positive;The object side surface of second lens is concave, and its optical power is negative;The object side surface of third lens is convex, and its optical power is positive;The object side surface of fourth lens is concave, and its optical power is negative;Optical system satisfies: 16.0 °·mm<2FOV / (TTL / ImgH / EPD)<21.7 °·mm.On the other hand, the application embodiment also provides a kind of camera module.The optical system and camera module of the application embodiment are mainly composed of 4 lenses, and the number of lenses is less, the structure is simple, easy to process and install, realize the compact, light weight and high performance collaborative design.

Description

Technical fields: This application relates to an optical system and a camera module for its application, and more particularly to an aerial photography optical system and a camera module for its application. Background technology: With the increasing application of drone aerial photography, aerial lenses must achieve lightweight design under strict constraints on overall length and weight, while also possessing high resolution and low distortion imaging capabilities to meet the demand for clear capture of ground details in high-altitude photography. However, existing aerial lenses typically improve image quality by increasing the number of lenses or adopting complex surface shapes, resulting in a large number of lenses, large size, and complex structure. Summary of the Invention: To overcome the problems of existing aerial photography lenses having a large number of lenses, large size, and complex structure, this application provides an aerial photography optical system.

[0004] An aerial photography optical system comprises, in sequence along the optical axis from the object side to the imaging plane side: a first lens, a second lens, a third lens, and a fourth lens; The object side of the first lens is convex, and its optical power is positive. The object side of the second lens is concave, and its optical power is negative. The object-side surface of the third lens is convex, the image-side surface is convex, and its optical power is positive. The fourth lens has a concave object side and a convex image side, and its optical power is negative. The optical system meets the following requirement: 16.0 °·mm < 2 FOV / (TTL / ImgH / EPD)<21.7°·mm; Wherein, FOV is half of the maximum field of view of the imaging optical system, TTL is the on-axis distance from the object side of the first lens to the imaging surface, ImgH is half of the diagonal length of the effective pixel area on the imaging surface, and EPD is the entrance pupil diameter of the optical imaging lens.

[0005] On the other hand, this application also provides a camera module.

[0006] A camera module includes at least an optical lens, and the aerial photography optical system described above is installed inside the optical lens.

[0007] The optical system and camera module of this application embodiment are mainly composed of four lenses in an optimized combination. The small number of lenses and simple structure make it easy to manufacture and install, achieving a synergistic design of compactness, lightweight and high performance. By combining different lenses, rationally allocating optical power and surface shape, and optimizing the optical performance parameters of the optical system, the lens achieves optimal matching of total optical length, image plane size and entrance pupil diameter under the set field of view. This effectively suppresses the incident angle of the principal ray at the edge of the field of view and clearly restores the details of the subject. Thus, it achieves a synergy of low distortion, high edge illumination and high resolution in a compact structure, meeting the stringent requirements of high-fidelity imaging for aerial photography applications and improving the overall image quality and information fidelity of UAV aerial images. Attached image description: To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of the structure of an embodiment of the optical system or camera module of this application; Figure 2 The on-axis chromatic aberration, astigmatism, and distortion curves are for an embodiment of the optical system or camera module of this application. Figure 3 This is a schematic diagram of the structure of the optical system or camera module of this application, according to Embodiment 2. Figure 4 The on-axis chromatic aberration, astigmatism, and distortion curves are for Embodiment 2 of the optical system or camera module of this application. Figure 5 This is a schematic diagram of the structure of the optical system or camera module of Embodiment 3 of this application; Figure 6 The on-axis chromatic aberration, astigmatism, and distortion curves are for Embodiment 3 of the optical system or camera module of this application. Figure 7 This is a schematic diagram of the structure of the optical system or camera module of Embodiment 4 of this application; Figure 8 The graph shows the on-axis chromatic aberration, astigmatism, and distortion curves for Embodiment 4 of the optical system or camera module of this application. Detailed implementation method: To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0011] When ordinal numbers such as "first" and "second" are mentioned in the embodiments of this application, unless they actually express the meaning of order according to the context, they should be understood as being used only for distinction.

[0012] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0013] This application provides an aerial photography optical system, which includes, along the optical axis from the object side to the imaging plane side, a first lens, a second lens, a third lens, and a fourth lens. The object side of the first lens is convex, and its optical power is positive. The object side of the second lens is concave, and its optical power is negative. The object side and image side of the third lens are both convex, and its optical power is positive. The object side and image side of the fourth lens are both concave, and its optical power is negative. The optical system satisfies the following condition: 16.0 °·mm < 2. FOV / (TTL / ImgH / EPD)<21.7 °·mm; where FOV is half of the maximum field of view of the imaging optical system, TTL is the on-axis distance from the object side of the first lens to the imaging plane, ImgH is half of the diagonal length of the effective pixel area on the imaging plane, and EPD is the entrance pupil diameter of the optical imaging lens.

[0014] The optical system of this application embodiment is mainly composed of four lenses in an optimized combination. The small number of lenses and simple structure make it easy to manufacture and install, achieving a synergistic design of compactness, lightweight, and high performance. By combining different lenses, rationally allocating optical power and surface shape, and optimizing the optical performance parameters of the optical system, the system ensures that the lens achieves optimal matching of total optical length, image plane size, and entrance pupil diameter under a set field of view. This effectively suppresses the incident angle of the principal ray at the edge of the field of view, clearly restoring the details of the photographed object. Thus, it achieves a synergy of low distortion, high edge illumination, and high resolution in a compact structure, meeting the stringent requirements of high-fidelity imaging for aerial photography applications and improving the overall image quality and information fidelity of UAV aerial images.

[0015] Furthermore, as a preferred embodiment of this solution and not a limitation, the optical system satisfies the following conditions: the F-number of the optical system ≤ 4.02, and the overall length ≤ 29.00 mm. This achieves a synergy of compactness, lightweight design, and high performance.

[0016] Furthermore, as a preferred embodiment of this solution and not a limitation, the optical system satisfies: 5.2 ° / mm < 2 FOV / ImgH<8.6 ° / mm; where FOV is half of the maximum field angle of the imaging optical system, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface. This can effectively control the proportional relationship between the field angle of the lens and the image plane size, ensure the precise matching between the field angle and the image plane size, facilitate the compact design of the system, with small distortion and obvious edge illumination.

[0017] Still further, as a preferred but non-limiting embodiment of the present solution, the optical system satisfies: 10.1 mm<f1 f3 / f<15.5 mm; where f1 is the effective focal length of the first lens, f3 is the effective focal length of the third lens, and f is the effective focal length of the optical imaging system. This can reasonably distribute the optical power contributions of the first lens and the third lens, ensure that the two form an effective aberration complementary relationship in the system, avoid the deterioration of spherical aberration and coma caused by unbalanced optical power distribution, and simultaneously control the lens surface sensitivity to improve the tolerance latitude for processing and assembly, so as to achieve a balance between high resolution and favorable manufacturability.

[0018] Furthermore, as a preferred but non-limiting embodiment of the present solution, the optical system satisfies: -3.1<f34 / f12<0; where f12 is the combined focal length of the first lens and the second lens, and f34 is the combined focal length of the third lens and the fourth lens. By reasonably controlling the ratio of the combined focal length of the first and second lenses to the combined focal length of the third and fourth lenses, the optical power of these four lenses can be properly distributed, so as to realize the balance of internal aberrations of the optical lens, further facilitate the adjustment of field curvature and astigmatism at the edge field of view of the optical lens, and meet the imaging quality requirements of the optical lens for the surrounding environment.

[0019] Still further, as a preferred but non-limiting embodiment of the present solution, the optical system satisfies: 1.1<|f3-f4| / |f3+f4|<5.6; where f3 is the effective focal length of the third lens, and f4 is the effective focal length of the fourth lens. By reasonably controlling the focal length ratio of the third lens and the fourth lens, the optical system can obtain higher imaging resolution, which is beneficial to expanding the field angle range of the optical system.

[0020] Still further, as a preferred but non-limiting embodiment of the present solution, the optical system satisfies: 6.2 mm<|f3 f4| / f<12.5 mm; where f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, and f is the effective focal length of the optical imaging system. By reasonably controlling the ratio of the combined optical power of the third lens and the fourth lens to the total optical power of the system, the optical system can obtain favorable aberration balance and a compact structure.

[0021] Furthermore, as a preferred embodiment of this solution and not a limitation, the optical system satisfies: 0.3 < |(R5-R6) / R6| < 4.6; where R5 is the radius of curvature of the object-side surface of the third lens, and R6 is the radius of curvature of the image-side surface of the third lens. By controlling the ratio of the radii of curvature of the object-side surface and the image-side surface of the third lens, a smooth transition in the light deflection angle between the two adjacent surfaces is achieved, avoiding high-order aberrations caused by abrupt changes in surface shape, and preventing the curvatures of the two surfaces from being too close, which would increase the processing sensitivity. Thus, the manufacturability and assembly yield of the system are improved while ensuring good aberration correction.

[0022] Furthermore, as a preferred embodiment of this solution, and not a limitation, the optical system satisfies: 0.5 < (T12 + T23) / BFL < 4.4; where T12 is the air gap between the first and second lenses on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, and BFL is the shortest distance along the optical axis from the image side of the ninth lens to the imaging surface of the optical system. By limiting the range of the above relationship, the optical back focus is controlled within a reasonable range, effectively ensuring the matching degree between the image and the image sensor, and guaranteeing the matching performance between the optical system and the image sensor; at the same time, the on-axis distances between the first and second lenses, as well as between the second and third lenses, are controlled, which is beneficial to the assembly process, avoids light interference caused by the two lenses being too close, reduces the sensitivity of the lenses, weakens the ghost energy between the first and second lenses, and improves the image quality of the lens.

[0023] Furthermore, as a preferred embodiment of this solution, and not a limitation, the optical system satisfies: 8.5 < (CT2 + CT3 + CT4) / BFL < 21.3; where CT2 is the center thickness of the second lens along the optical axis, CT3 is the center thickness of the third lens along the optical axis, CT4 is the center thickness of the fourth lens along the optical axis, and BFL is the shortest distance along the optical axis from the image side of the eighth lens to the imaging surface of the optical system. By limiting the range of the above relationship, the ratio of the total center thickness of the second to fourth lenses to the optical back focal length can be adjusted, ensuring that the intermediate group has sufficient material thickness to bear the refractive power and suppress higher-order aberrations, while avoiding insufficient space for filter or protective glass installation due to an excessively short back focal length, or redundancy in the overall system length caused by an excessively large total thickness of the intermediate group. This condition, while ensuring the aberration compensation capability and packaging feasibility of the intermediate group, leaves sufficient aberration correction space for the rear group, enabling the system to achieve the best balance between spherical aberration, coma, and field curvature within a compact overall length.

[0024] Further, as a preferred but non-limiting embodiment of the present solution, the optical system satisfies: 1.4 < EPD / (T12+T23) < 5.4; where T12 is the air interval on the optical axis between the first lens and the second lens, T23 is the air interval on the optical axis between the second lens and the third lens, and EPD is the entrance pupil diameter of the optical imaging lens. By limiting the range of the above relational expression, the proportional relationship between the total air interval from the first lens to the third lens and the entrance pupil diameter can be optimized, ensuring that the middle group has sufficient light deflection space to disperse the dioptric burden of each mirror surface, while avoiding excessive interval leading to redundant total system length or too small interval causing sharp light bending and generating high-order aberrations, thereby realizing a compact system structure on the premise of ensuring good aberration correction.

[0025] Embodiment 1: Specifically, in combination with Figure 1 , in this embodiment, the present optical system sequentially includes, from the object side to the image plane S11 side along the optical axis: a first lens E1, an STO, a second lens E2, a third lens E3, a fourth lens E4, and an infrared filter E5.

[0026] The first lens E1 has positive refractive power, with its object side surface S1 being a convex surface and its image side surface S2 being a concave surface. The second lens E2 has negative refractive power, with its object side surface S3 being a concave surface and its image side surface S4 being a concave surface. The third lens E3 has positive refractive power, with its object side surface S5 being a convex surface and its image side surface S6 being a convex surface. The fourth lens E4 has negative refractive power, with its object side surface S7 being a concave surface and its image side surface S8 being a convex surface. The filter E5 has an object side surface S9 and an image side surface S10. Light from an object sequentially passes through the respective surfaces S1 to S10 and finally forms an image on the image plane S11.

[0027] The basic parameters of the optical system in this embodiment are shown in the following table:

[0028] Figure 2 shows the longitudinal chromatic aberration, astigmatism and distortion curves of Embodiment 1. Longitudinal chromatic aberration represents the focal point deviation of light of different wavelengths after passing through the lens; astigmatism represents the tangential image surface curvature and the sagittal image surface curvature; distortion represents the corresponding distortion magnitude values at different image heights. From Figure 2 , it can be seen that the optical system in this embodiment can achieve good imaging quality.

[0029] Embodiment 2: Specifically, in combination with Figure 3 , in this embodiment, the present optical system sequentially includes, from the object side to the image plane S11 side along the optical axis: a first lens E1, an STO, a second lens E2, a third lens E3, a fourth lens E4, and an infrared filter E5.

[0030] The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being convex. The second lens E2 has negative optical power, with its object-side surface S3 being concave and its image-side surface S4 being convex. The third lens E3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The fourth lens E4 has negative optical power, with its object-side surface S7 being concave and its image-side surface S8 being convex. The filter E5 has an object-side surface S9 and an image-side surface S10. Light from the object passes sequentially through each surface S1 to S10 and is finally imaged on the imaging surface S11.

[0031] The basic parameters of the optical system in this embodiment are shown in the table below:

[0032] Figure 4 The diagram shows the on-axis chromatic aberration, astigmatism, and distortion curves for Example 2. On-axis chromatic aberration represents the deviation of the focal point of light of different wavelengths after passing through the lens; astigmatism represents the curvature of the meridional and sagittal image planes; and distortion represents the magnitude of distortion at different image heights. From... Figure 4 As can be seen, the optical system in this embodiment can achieve good imaging quality.

[0033] Example 3: Specifically, in combination with Figure 5 In this embodiment, the optical system includes, in sequence along the optical axis from the object side to the imaging surface S11 side: a first lens E1, a third lens E3, a fourth lens E4, and an infrared filter E5.

[0034] The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has negative optical power, with its object-side surface S3 being concave and its image-side surface S4 being convex. The third lens E3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The fourth lens E4 has negative optical power, with its object-side surface S7 being concave and its image-side surface S8 being convex. The filter E5 has an object-side surface S9 and an image-side surface S10. Light from the object passes sequentially through each surface S1 to S10 and is finally imaged on the imaging surface S11.

[0035] The basic parameters of the optical system in this embodiment are shown in the table below:

[0036] Figure 6 The diagram shows the on-axis chromatic aberration, astigmatism, and distortion curves for Example 3. On-axis chromatic aberration represents the deviation of the focal point of light of different wavelengths after passing through the lens; astigmatism represents the curvature of the meridional and sagittal image planes; and distortion represents the magnitude of distortion at different image heights. From... Figure 6 As can be seen, the optical system in this embodiment can achieve good imaging quality.

[0037] Example 4: Specifically, in combination with Figure 7 In this embodiment, the optical system includes, in sequence along the optical axis from the object side to the imaging surface S11 side: a first lens E1, a third lens E3, a fourth lens E4, and an infrared filter E5.

[0038] The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has negative optical power, with its object-side surface S3 being concave and its image-side surface S4 being convex. The third lens E3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The fourth lens E4 has negative optical power, with its object-side surface S7 being concave and its image-side surface S8 being concave. The filter E5 has an object-side surface S9 and an image-side surface S10. Light from the object passes sequentially through each surface S1 to S10 and is finally imaged on the imaging surface S11.

[0039] The basic parameters of the optical system in this embodiment are shown in the table below:

[0040] Figure 8 The diagram shows the on-axis chromatic aberration, astigmatism, and distortion curves for Example 4. On-axis chromatic aberration represents the deviation of the focal point of light of different wavelengths after passing through the lens; astigmatism represents the curvature of the meridional and sagittal image planes; and distortion represents the magnitude of distortion at different image heights. From... Figure 8 As can be seen, the optical system in this embodiment can achieve good imaging quality.

[0041] The basic data of each optical system in the above embodiments one to four are as follows:

[0042] In the above embodiments one to four, the conditional expressions of each optical system in the corresponding embodiments satisfy the conditions in the table below:

[0043] A camera module includes at least an optical lens, and the aerial photography optical system described above is installed inside the optical lens.

[0044] The camera module of this application embodiment is mainly composed of four lenses in an optimized combination. The small number of lenses and simple structure make it easy to manufacture and install, achieving a synergistic design of compactness, lightweight, and high performance. By combining different lenses, rationally allocating optical power and surface shape, and optimizing the optical performance parameters of the optical system, the lens achieves optimal matching of total optical length, image plane size, and entrance pupil diameter under a set field of view. This effectively suppresses the incident angle of the principal ray at the edge of the field of view, clearly restores the details of the subject, and thus achieves a synergy of low distortion, high edge illumination, and high resolution in a compact structure. This meets the stringent requirements of high-fidelity imaging for aerial photography applications and improves the overall image quality and information fidelity of UAV aerial images.

[0045] The above description provides one or more embodiments in conjunction with specific content, and does not imply that the specific implementation of this application is limited to these descriptions. Any methods or structures that are similar to or identical to those of this application, or any technical deductions or substitutions made based on the concept of this application, should be considered within the scope of protection of this application.

Claims

1. An aerial photography optical system, comprising, along the optical axis from the object side to the imaging plane side, the following components in sequence: a first lens, a second lens, a third lens, and a fourth lens; characterized in that, the object-side surface of the first lens is convex, and has positive optical power; the object-side surface of the second lens is concave, and has negative optical power; the object-side surface of the third lens is convex, the image-side surface thereof is convex, and the third lens has positive optical power; the object-side surface of the fourth lens is concave, the image-side surface thereof is convex, and the fourth lens has negative optical power; The optical system meets the following requirement: 16.0 °·mm < 2 FOV / (TTL / ImgH / EPD)<21.7°·mm; wherein FOV is half of the maximum field of view of the imaging optical system, TTL is the on-axis distance from the object-side surface of the first lens to the imaging plane, ImgH is half of the diagonal length of the effective pixel area on the imaging plane, and EPD is the entrance pupil diameter of the optical imaging lens.

2. The aerial photography optical system as described in claim 1, characterized in that, The optical system meets the following requirement: 5.2 ° / mm < 2 FOV / ImgH < 8.6 ° / mm; where FOV is half of the maximum field of view of the imaging optical system, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface.

3. The aerial photography optical system as claimed in claim 1 or 2, characterized in that, The optical system meets the following requirement: 10.1 mm <f1 f3 / f < 15.5 mm; where f1 is the effective focal length of the first lens, f3 is the effective focal length of the third lens, and f is the effective focal length of the optical imaging system; and / or the optical system satisfies: -3.1<f34 / f12<0; where f12 is the combined focal length of the first lens and the second lens, and f34 is the combined focal length of the third lens and the fourth lens.

4. The aerial photography optical system as described in claim 1 or 2, characterized in that, the optical system satisfies: 1.1<|f3-f4| / |f3+f4|<5.6; where f3 is the effective focal length of the third lens, and f4 is the effective focal length of the fourth lens.

5. The aerial photography optical system as described in claim 1 or 2, characterized in that, The optical system satisfies: 6.2 mm < |f3 f4| / f<12.5 mm; where f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, and f is the effective focal length of the optical imaging system.

6. The aerial photography optical system as described in claim 1 or 2, characterized in that, the optical system satisfies: 0.3<|(R5-R6) / R6|<4.6; where R5 is the radius of curvature of the object-side surface of the third lens, and R6 is the radius of curvature of the image-side surface of the third lens.

7. The aerial photography optical system as described in claim 1 or 2, characterized in that, the optical system satisfies: 0.5<(T12+T23) / BFL<4.4; where T12 is the air gap on the optical axis between the first lens and the second lens, T23 is the air gap on the optical axis between the second lens and the third lens, and BFL is the shortest distance in the optical axis direction from the image-side surface of the ninth lens to the imaging plane of the optical system.

8. The aerial photography optical system as described in claim 1 or 2, characterized in that, the optical system satisfies: 8.5<(CT2+CT3+CT4) / BFL<21.3; where CT2 is the center thickness of the second lens on the optical axis, CT3 is the center thickness of the third lens on the optical axis, CT4 is the center thickness of the fourth lens on the optical axis, and BFL is the shortest distance in the optical axis direction from the image-side surface of the eighth lens to the imaging plane of the optical system.

9. The aerial photography optical system as described in claim 1 or 2, characterized in that, the optical system satisfies: 1.4<EPD / (T12+T23)<5.4; where T12 is the air gap on the optical axis between the first lens and the second lens, T23 is the air gap on the optical axis between the second lens and the third lens, and EPD is the entrance pupil diameter of the optical imaging lens.

10. A camera module, comprising at least an optical lens, characterized in that, An optical lens is installed with the aerial photography optical system as described in any one of claims 1 to 9.

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