A 25mm half-frame aerial lens

Abstract

The application discloses a 25mm half-frame aerial photography lens and relates to the technical field of optical lenses. The 25mm half-frame aerial photography lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a photosensitive chip arranged from an object side to an image side. Each lens satisfies the following conditional expressions: -1.2<F1 / F<-0.8, 0.4<F2 / F<0.6, -0.5<F3 / F<-0.3, 0.4<F4 / F<0.8, 0.4<F5 / F<0.8, -1.3<F6 / F<-1, wherein F1 is the focal length of the first lens, F2 is the focal length of the second lens, F3 is the focal length of the third lens, F4 is the focal length of the fourth lens, F5 is the focal length of the fifth lens, F6 is the focal length of the sixth lens, and F is the focal length of the optical lens. The 25mm half-frame aerial photography lens has the performances of high pixels, low distortion, high relative luminance and low chromatic aberration under the premise of half frame.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and in particular to a 25mm half-frame aerial photography lens. Background Technology

[0002] With the development of drone technology, the demand for optical lenses suitable for aerial photography is also gradually increasing. In order to obtain high-definition, uniform images, lenses suitable for aerial photography need to meet the requirements of high pixel count, low distortion, and high relative illumination.

[0003] Currently, aerial lenses that meet the requirements of high resolution, low distortion, and high relative illumination all have relatively small target surfaces. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a 25mm APS-C aerial lens that, while maintaining APS-C resolution, also features high resolution, low distortion, high relative illumination, and low chromatic aberration.

[0005] According to an embodiment of the present invention, a 25mm half-frame aerial camera lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a photosensitive chip arranged sequentially along the optical axis from the object side to the image side.

[0006] The first lens has negative optical power, the second lens has positive optical power, the third lens has negative optical power, the fourth lens has positive optical power, the fifth lens has positive optical power, and the sixth lens has negative optical power.

[0007] The first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens each satisfy the following conditional expression:

[0008] -1.2 < F1 / F < -0.8,

[0009] 0.4 < F² / F < 0.6

[0010] -0.5 < F3 / F < -0.3,

[0011] 0.4 < F4 / F < 0.8

[0012] 0.4 < F5 / F < 0.8

[0013] -1.3 < F6 / F < -1,

[0014] in,

[0015] F1 is the focal length of the first lens, F2 is the focal length of the second lens, F3 is the focal length of the third lens, F4 is the focal length of the fourth lens, F5 is the focal length of the fifth lens, F6 is the focal length of the sixth lens, and F is the focal length of the optical lens.

[0016] The 25mm half-frame aerial lens according to an embodiment of the present invention has at least the following beneficial effects: the first lens has negative optical power, which can bring light from a larger field of view into the lens and reduce the field of view of the subsequent lens; the sixth lens also has negative optical power, which is beneficial to increase the incident angle of light reaching the photosensitive chip (i.e., the image plane), thereby effectively improving relative illumination and increasing the image plane; the lenses that satisfy the condition work together to correct the principal ray aberration, so that the magnification of different fields of view is basically the same, and the distortion can be controlled within the range of 0.6%, ensuring the similarity between the object and the image.

[0017] According to some embodiments of the present invention, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens respectively satisfy the following conditional expressions:

[0018] 1.5 < Nd1 < 1.7,

[0019] 1.6 < Nd2 < 1.8,

[0020] 1.5 < Nd3 < 1.7

[0021] 1.7 < Nd4 < 1.9

[0022] 1.4 < Nd5 < 1.6,

[0023] 1.5 < Nd6 < 1.7

[0024] in,

[0025] Nd1 is the refractive index of the first lens, Nd2 is the refractive index of the second lens, Nd3 is the refractive index of the third lens, Nd4 is the refractive index of the fourth lens, Nd5 is the refractive index of the fifth lens, and Nd6 is the refractive index of the sixth lens.

[0026] According to some embodiments of the present invention, the object-side surface of the first lens is convex, and the image-side surface of the first lens is concave.

[0027] According to some embodiments of the present invention, both sides of the second lens are convex surfaces, and the curvature of the object-side surface of the second lens is greater than the curvature of the image-side surface of the second lens.

[0028] According to some embodiments of the present invention, both sides of the third lens are concave, and the curvature of the object-side surface of the third lens is less than the curvature of the image-side surface of the third lens.

[0029] According to some embodiments of the present invention, the object-side surface of the fourth lens is convex, and the image-side surface of the fourth lens is concave.

[0030] According to some embodiments of the present invention, both sides of the fifth lens are convex, and the curvature of the object-side surface of the fifth lens is greater than the curvature of the image-side surface of the fifth lens.

[0031] According to some embodiments of the present invention, the object-side surface of the sixth lens is concave, and the image-side surface of the sixth lens is convex.

[0032] According to some embodiments of the present invention, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens respectively satisfy the following conditional expressions:

[0033] 55 < Vd1 < 65,

[0034] 50 < Vd2 < 60,

[0035] 30 < Vd3 < 40

[0036] 30 < Vd4 < 40

[0037] 75 < Vd5 < 85,

[0038] 30 < Vd6 < 40,

[0039] in,

[0040] Vd1 is the dispersion coefficient of the first lens, Vd2 is the dispersion coefficient of the second lens, Vd3 is the dispersion coefficient of the third lens, Vd4 is the dispersion coefficient of the fourth lens, Vd5 is the dispersion coefficient of the fifth lens, and Vd6 is the dispersion coefficient of the sixth lens.

[0041] According to some embodiments of the present invention, an aperture stop is provided between the fourth lens and the fifth lens, and the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens respectively satisfy the following conditional expressions:

[0042] 0.08 < A01 / TL < 0.2

[0043] 0.05 < A02 < 0.2,

[0044] 0.1 < A03 < 1,

[0045] 1.5 < AS1 + AS2 < 4

[0046] 1 < AS1 / AS2 < 2,

[0047] 0.08 < A05 / TL < 0.12

[0048] 0.3 < BF / TL < 0.45

[0049] in,

[0050] A01 is the air gap between the first lens and the second lens, A02 is the air gap between the second lens and the third lens, A03 is the air gap between the third lens and the fourth lens, AS1 is the air gap between the fourth lens and the aperture stop, AS2 is the air gap between the aperture stop and the fifth lens, A05 is the air gap between the fifth lens and the sixth lens, BF is the back focal length of the optical lens, and TL is the overall length of the optical lens.

[0051] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0053] Figure 1 This is a schematic diagram of the structure of the 25mm half-frame aerial lens according to an embodiment of the present invention;

[0054] Figure 2 This is the MTF curve of an optical lens according to an embodiment of the present invention;

[0055] Figure 3 This is a blur pattern of an optical lens according to an embodiment of the present invention;

[0056] Figure 4 The field curvature and distortion curves of an optical lens according to an embodiment of the present invention;

[0057] Figure 5 This is a relative illumination diagram of an optical lens according to an embodiment of the present invention.

[0058] Icon labels:

[0059] First lens 100, second lens 200, third lens 300, fourth lens 400, fifth lens 500, sixth lens 600, photosensitive chip 700, aperture 800, protective glass 900. Detailed Implementation

[0060] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0061] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0062] In the description of this invention, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features or their sequential relationship.

[0063] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0064] Reference Figure 1 As shown, a 25mm half-frame aerial lens according to an embodiment of the present invention includes a first lens 100, a second lens 200, a third lens 300, a fourth lens 400, a fifth lens 500, a sixth lens 600 and a photosensitive chip 700 arranged sequentially along the optical axis from the object side to the image side.

[0065] The first lens 100 has negative optical power, the second lens 200 has positive optical power, the third lens 300 has negative optical power, the fourth lens 400 has positive optical power, the fifth lens 500 has positive optical power, and the sixth lens 600 has negative optical power.

[0066] The first lens 100, the second lens 200, the third lens 300, the fourth lens 400, the fifth lens 500, and the sixth lens 600 respectively satisfy the following conditional expressions:

[0067] -1.2 < F1 / F < -0.8,

[0068] 0.4 < F² / F < 0.6

[0069] -0.5 < F3 / F < -0.3,

[0070] 0.4 < F4 / F < 0.8

[0071] 0.4 < F5 / F < 0.8

[0072] -1.3 < F6 / F < -1,

[0073] in,

[0074] F1 is the focal length of the first lens 100, F2 is the focal length of the second lens 200, F3 is the focal length of the third lens 300, F4 is the focal length of the fourth lens 400, F5 is the focal length of the fifth lens 500, F6 is the focal length of the sixth lens 600, and F is the focal length of the optical lens.

[0075] Typically, the image sensor 700 is a CMOS (Metal-Oxide-Semiconductor) device used to capture imaging signals and form an image. The first lens 100, second lens 200, third lens 300, fourth lens 400, fifth lens 500, and sixth lens 600 can all use glass lenses, offering a wide temperature range. It should be understood that a protective glass 900 can also be placed between the sixth lens 600 and the image sensor 700. The thickness of the protective glass 900 can be selected as 2.5 mm.

[0076] Preferably, the object-side surface of the first lens 100 is convex, and the image-side surface of the first lens 100 is concave; both sides of the second lens 200 are convex, and the curvature of the object-side surface of the second lens 200 is greater than the curvature of the image-side surface of the second lens 200; both sides of the third lens 300 are concave, and the curvature of the object-side surface of the third lens 300 is less than the curvature of the image-side surface of the third lens 300; the object-side surface of the fourth lens 400 is convex, and the image-side surface of the fourth lens 400 is concave; both sides of the fifth lens 500 are convex, and the curvature of the object-side surface of the fifth lens 500 is greater than the curvature of the image-side surface of the fifth lens 500; the object-side surface of the sixth lens 600 is concave, and the image-side surface of the sixth lens 600 is convex. The first lens 100 has negative optical power, with a convex surface facing the object and a concave surface facing the image, resembling a crescent shape. This allows it to capture light from a larger field of view, reducing the field of view of the subsequent lens. The sixth lens 600 also has negative optical power, which helps to increase the angle of incidence of light reaching the image sensor 700, thereby effectively improving relative illumination and increasing the image size. All lenses satisfy the above conditions and work together to correct principal ray aberration. The magnification is essentially the same across different fields of view, keeping distortion within 0.6% and ensuring similarity between the object and image.

[0077] It is understandable that the first lens 100, the second lens 200, the third lens 300, the fourth lens 400, the fifth lens 500, and the sixth lens 600 respectively satisfy the following conditional expressions:

[0078] 1.5 < Nd1 < 1.7,

[0079] 1.6 < Nd2 < 1.8,

[0080] 1.5 < Nd3 < 1.7

[0081] 1.7 < Nd4 < 1.9

[0082] 1.4 < Nd5 < 1.6

[0083] 1.5 < Nd6 < 1.7

[0084] in,

[0085] Nd1 is the refractive index of the first lens 100, Nd2 is the refractive index of the second lens 200, Nd3 is the refractive index of the third lens 300, Nd4 is the refractive index of the fourth lens 400, Nd5 is the refractive index of the fifth lens 500, and Nd6 is the refractive index of the sixth lens 600.

[0086] It is important to understand that refractive index refers to the refractive index value of optical glass at a standard temperature (20°C) and a standard wavelength (587.56 nm). In some embodiments, both the second lens 200 and the fourth lens 400 are made of high-refractive-index materials, coupled with positive optical power, effectively reducing their spherical aberration and coma. The object-side surface of the fourth lens 400 is convex, and the image-side surface is concave, also resembling a meniscus shape. Combined with the high-refractive-index material, this helps to reduce its field curvature.

[0087] It is understandable that the first lens 100, the second lens 200, the third lens 300, the fourth lens 400, the fifth lens 500, and the sixth lens 600 respectively satisfy the following conditional expressions:

[0088] 55 < Vd1 < 65,

[0089] 50 < Vd2 < 60,

[0090] 30 < Vd3 < 40

[0091] 30 < Vd4 < 40

[0092] 75 < Vd5 < 85,

[0093] 30 < Vd6 < 40,

[0094] in,

[0095] Vd1 is the dispersion coefficient of the first lens 100, Vd2 is the dispersion coefficient of the second lens 200, Vd3 is the dispersion coefficient of the third lens 300, Vd4 is the dispersion coefficient of the fourth lens 400, Vd5 is the dispersion coefficient of the fifth lens 500, and Vd6 is the dispersion coefficient of the sixth lens 600.

[0096] The dispersion coefficients of each lens satisfy the above-mentioned conditional equation. The dispersion coefficients are matched with each other, which helps to eliminate chromatic aberration of the optical lens and provide high-resolution color images.

[0097] It is understandable that an aperture stop 800 is provided between the fourth lens 400 and the fifth lens 500, and the first lens 100, the second lens 200, the third lens 300, the fourth lens 400, the fifth lens 500 and the sixth lens 600 respectively satisfy the following conditional expressions:

[0098] 0.08 < A01 / TL < 0.2

[0099] 0.05 < A02 < 0.2,

[0100] 0.1 < A03 < 1,

[0101] 1.5 < AS1 + AS2 < 4

[0102] 1 < AS1 / AS2 < 2,

[0103] 0.08 < A05 / TL < 0.12

[0104] 0.3 < BF / TL < 0.45

[0105] in,

[0106] A01 is the air gap between the first lens 100 and the second lens 200; A02 is the air gap between the second lens 200 and the third lens 300; A03 is the air gap between the third lens 300 and the fourth lens 400; AS1 is the air gap between the fourth lens 400 and the aperture stop 800; AS2 is the air gap between the aperture stop 800 and the fifth lens 500; A05 is the air gap between the fifth lens 500 and the sixth lens 600; BF is the back focal length of the optical lens; and TL is the overall length of the optical lens.

[0107] Example 1:

[0108] The optical lens has a focal length F of 25mm, an F / NO ratio of 5.6, an actual imaging target surface of φ29, and a total length TL of 49mm. The first lens 100 has a convex surface facing the object side and a concave surface facing the image side. The second lens 200 has convex surfaces on both sides, with the curvature of the object-side surface greater than that of the image-side surface. The third lens 300 has concave surfaces on both sides, with the curvature of the object-side surface less than that of the image-side surface. The fourth lens 400 has a convex surface facing the object side and a concave surface facing the image side. The fifth lens 500 has convex surfaces on both sides, with the curvature of the object-side surface greater than that of the image-side surface. The sixth lens 600 has a concave surface facing the object side and a convex surface facing the image side. A protective glass 900 with a thickness of 2.5 mm is disposed between the sixth lens 600 and the photosensitive chip 700. An aperture stop 800 is disposed between the fourth lens 400 and the fifth lens 500. The specific parameters of the optical lens are shown in Table 1, wherein the surfaces are numbered sequentially along the optical axis from the object side to the image side to obtain surface numbers. For example, the surface of the first lens 100 facing the object side is S1, and the surface facing the image side is S2.

[0109] Table 1. Parameters of the optical lens in Example 1

[0110]

[0111] In Table 1, Infinity refers to infinity. Optical performance tests were conducted on the optical lens implementing step 1, and the results are shown in the figure. Figure 2 The MTF curve of the optical lens in Example 1 is used to evaluate the resolving power of the optical lens. As can be seen from the curve, the MTF curves under each field of view are relatively concentrated and there is no large dispersion, which proves that the various aberrations are well corrected and the consistency of each field of view is good. Figure 3 The image shows the diffusion pattern of the optical lens in Example 1. As can be seen from the results, the light rays in each field of view converge very closely, approaching the diffraction limit, which proves that the optical lens has a very good imaging effect. Figure 4 The field curvature and distortion curves of the optical lens in Example 1 are shown in the figure. It can be seen from the results that the distortion is controlled below 0.6%. Figure 5 The image shows the relative illumination of the optical lens in Example 1. The relative illumination of the edge field of view of this optical lens can reach more than 68%.

[0112] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A 25mm APS-C aerial lens, characterized in that, include: A first lens (100), a second lens (200), a third lens (300), a fourth lens (400), a fifth lens (500), a sixth lens (600), and a photosensitive chip (700) are arranged sequentially from the object side to the image side along the optical axis. The first lens (100) has negative optical power, the second lens (200) has positive optical power, the third lens (300) has negative optical power, the fourth lens (400) has positive optical power, the fifth lens (500) has positive optical power, and the sixth lens (600) has negative optical power. The first lens (100), the second lens (200), the third lens (300), the fourth lens (400), the fifth lens (500), and the sixth lens (600) respectively satisfy the following conditional expressions: -1.2 < F1 / F < -0.8, 0.4 < F² / F < 0.6 -0.5 < F3 / F < -0.3, 0.4 < F4 / F < 0.8 0.4 < F5 / F < 0.8 -1.3 < F6 / F < -1, in, F1 is the focal length of the first lens (100), F2 is the focal length of the second lens (200), F3 is the focal length of the third lens (300), F4 is the focal length of the fourth lens (400), F5 is the focal length of the fifth lens (500), F6 is the focal length of the sixth lens (600), and F is the focal length of the lens.

2. The 25mm APS-C aerial lens according to claim 1, characterized in that, The first lens (100), the second lens (200), the third lens (300), the fourth lens (400), the fifth lens (500), and the sixth lens (600) respectively satisfy the following conditional expressions: 1.5 < Nd1 < 1.7, 1.6 < Nd2 < 1.8, 1.5 < Nd3 < 1.7 1.7 < Nd4 < 1.9 1.4 < Nd5 < 1.6, 1.5 < Nd6 < 1.7 in, Nd1 is the refractive index of the first lens (100), Nd2 is the refractive index of the second lens (200), Nd3 is the refractive index of the third lens (300), Nd4 is the refractive index of the fourth lens (400), Nd5 is the refractive index of the fifth lens (500), and Nd6 is the refractive index of the sixth lens (600).

3. The 25mm APS-C aerial lens according to claim 1, characterized in that, The object-side surface of the first lens (100) is convex, and the image-side surface of the first lens (100) is concave.

4. The 25mm APS-C aerial lens according to claim 1, characterized in that, Both sides of the second lens (200) are convex, and the curvature of the object-side surface of the second lens (200) is greater than the curvature of the image-side surface of the second lens (200).

5. The 25mm APS-C aerial lens according to claim 1, characterized in that, Both sides of the third lens (300) are concave, and the curvature of the object-side surface of the third lens (300) is less than the curvature of the image-side surface of the third lens (300).

6. The 25mm APS-C aerial lens according to claim 1, characterized in that, The fourth lens (400) has a convex surface facing the object side and a concave surface facing the image side.

7. The 25mm APS-C aerial lens according to claim 1, characterized in that, Both sides of the fifth lens (500) are convex, and the curvature of the object-side surface of the fifth lens (500) is greater than the curvature of the image-side surface of the fifth lens (500).

8. The 25mm APS-C aerial lens according to claim 1, characterized in that, The object-side surface of the sixth lens (600) is concave, and the image-side surface of the sixth lens (600) is convex.

9. The 25mm APS-C aerial lens according to claim 1, characterized in that, The first lens (100), the second lens (200), the third lens (300), the fourth lens (400), the fifth lens (500), and the sixth lens (600) respectively satisfy the following conditional expressions: 55 < Vd1 < 65, 50 < Vd2 < 60, 30 < Vd3 < 40 30 < Vd4 < 40 75 < Vd5 < 85, 30 < Vd6 < 40, in, Vd1 is the dispersion coefficient of the first lens (100), Vd2 is the dispersion coefficient of the second lens (200), Vd3 is the dispersion coefficient of the third lens (300), Vd4 is the dispersion coefficient of the fourth lens (400), Vd5 is the dispersion coefficient of the fifth lens (500), and Vd6 is the dispersion coefficient of the sixth lens (600).

10. The 25mm APS-C aerial lens according to claim 1, characterized in that, An aperture stop (800) is provided between the fourth lens (400) and the fifth lens (500). The first lens (100), the second lens (200), the third lens (300), the fourth lens (400), the fifth lens (500), and the sixth lens (600) respectively satisfy the following conditional expressions: 0.08 < A01 / TL < 0.2 0.05＜A02＜0.2， 0.1＜A03＜1， 1.5 < AS1 + AS2 < 4 1 < AS1 / AS2 < 2, 0.08 < A05 / TL < 0.12 0.3 < BF / TL < 0.45 in, A01 is the air gap between the first lens (100) and the second lens (200), A02 is the air gap between the second lens (200) and the third lens (300), A03 is the air gap between the third lens (300) and the fourth lens (400), AS1 is the air gap between the fourth lens (400) and the aperture stop (800), AS2 is the air gap between the aperture stop (800) and the fifth lens (500), A05 is the air gap between the fifth lens (500) and the sixth lens (600), BF is the back focal length of the lens, and TL is the overall length of the lens.

Images