25mm half-format aerial photography lens

Abstract

The invention, which relates to the technical field of the optical lens, discloses a 25mm half-format aerial photographing lens comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a photosensitive chip which are arranged from an object side to an image side. The lenses respectively meet 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, F1 being the focal length of the first lens, F2 being the focal length of the second lens, F3 being the focal length of the third lens, F4 being the focal length of the fourth lens, F5 being the focal length of the fifth lens, F6 being the focal length of the sixth lens, and F being the focal length of the optical lens. The 25mm half-frame aerial photographing lens disclosed by the invention also has the performances of high pixel, low distortion, high relative illumination and low chromatic aberration on the premise of a half frame.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and in particular to a 25mm half-frame aerial photography lens. Background Art

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

[0003] At present, the target surface of aerial photography lenses that can meet the requirements of high pixels, low distortion, and high relative illumination are relatively small. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a 25mm half-frame aerial photography lens that, while maintaining a half-frame format, also has the performance of high pixel count, low distortion, high relative illumination, and low chromatic aberration.

[0005] A 25mm half-frame aerial photography lens according to an embodiment of the present invention includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a photosensitive chip, which are arranged in sequence from the object side to the image side along the optical axis. 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; 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: -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, 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.

[0006] The 25mm half-frame aerial photography lens according to an embodiment of the present invention has at least the following beneficial effects: the first lens element has a negative optical power, which can collect light from a larger field of view into the lens, thereby reducing the field of view angle of the subsequent lens; the sixth lens element also has a negative optical power, which helps to increase the angle of incidence of light reaching the photosensitive chip (i.e., the image plane), thereby effectively improving the relative illumination and increasing the image plane; the lenses that meet the conditional formula 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 a range of 0.6%, ensuring the similarity between the object and the image.

[0007] 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 formulas: 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, 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.

[0008] According to some embodiments of the present invention, a surface of the first lens facing the object side is a convex surface, and a surface of the first lens facing the image side is a concave surface.

[0009] According to some embodiments of the present invention, both side surfaces of the second lens are convex, and the curvature of the surface of the second lens facing the object side is greater than the curvature of the surface of the second lens facing the image side.

[0010] According to some embodiments of the present invention, both side surfaces of the third lens are concave, and the curvature of the surface of the third lens facing the object side is smaller than the curvature of the surface of the third lens facing the image side.

[0011] According to some embodiments of the present invention, a surface of the fourth lens facing the object side is convex, and a surface of the fourth lens facing the image side is concave.

[0012] According to some embodiments of the present invention, both side surfaces of the fifth lens are convex, and a curvature of a surface of the fifth lens facing the object side is greater than a curvature of a surface of the fifth lens facing the image side.

[0013] According to some embodiments of the present invention, a surface of the sixth lens facing the object side is concave, and a surface of the sixth lens facing the image side is convex.

[0014] 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 formulas: 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, 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.

[0015] According to some embodiments of the present invention, a 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 formulas: 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 distance between the first lens and the second lens, A02 is the air distance between the second lens and the third lens, A03 is the air distance between the third lens and the fourth lens, AS1 is the air distance between the fourth lens and the aperture, AS2 is the air distance between the aperture and the fifth lens, A05 is the air distance between the fifth lens and the sixth lens, BF is the back focus of the optical lens, and TL is the overall length of the optical lens.

[0016] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which: Figure 1 This is a schematic structural diagram of a 25mm half-frame aerial photography lens according to an embodiment of the present invention; Figure 2 The MTF curve of the optical lens of an embodiment of the present invention; Figure 3 The dispersion pattern of the optical lens according to one embodiment of the present invention is shown below; Figure 4 Field curvature and distortion curves of an optical lens according to an embodiment of the present invention; Figure 5 This is a relative illumination diagram of an optical lens according to an embodiment of the present invention.

[0018] Figure Number: A first lens 100 , a second lens 200 , a third lens 300 , a fourth lens 400 , a fifth lens 500 , a sixth lens 600 , a photosensitive chip 700 , an aperture 800 , and a protective glass 900 . DETAILED DESCRIPTION

[0019] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0020] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] In the description of the present invention, "a plurality" refers to more than two. The use of "first" or "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of the indicated technical features, or implicitly indicating the order of the indicated technical features.

[0022] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0023] Reference Figure 1As shown, a 25mm half-frame aerial photography 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, which are sequentially arranged along the optical axis from the object side to the image side. 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 formulas: -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 optical lens.

[0024] Typically, the photosensitive chip 700 is a CMOS (metal oxide semiconductor) element, used to capture imaging signals and form images. The first lens 100, second lens 200, third lens 300, fourth lens 400, fifth lens 500, and sixth lens 600 can all be made of glass, which has a wide temperature range. It should be understood that a protective glass 900 can be placed between the sixth lens 600 and the photosensitive chip 700. The thickness of the protective glass 900 can be 2.5 mm.

[0025] Preferably, the surface of the first lens 100 facing the object side is convex, and the surface of the first lens 100 facing the image side is concave; both sides of the second lens 200 are convex, and the curvature of the surface of the second lens 200 facing the object side is greater than the curvature of the surface of the second lens 200 facing the image side; both sides of the third lens 300 are concave, and the curvature of the surface of the third lens 300 facing the object side is less than the curvature of the surface of the third lens 300 facing the image side; the surface of the fourth lens 400 facing the object side is convex, and the surface of the fourth lens 400 facing the image side is concave; both sides of the fifth lens 500 are convex, and the curvature of the surface of the fifth lens 500 facing the object side is greater than the curvature of the surface of the fifth lens 500 facing the image side; the surface of the sixth lens 600 facing the object side is concave, and the surface of the sixth lens 600 facing the image side is convex. The first lens 100 has negative optical power, with a convex surface facing the object side and a concave surface facing the image side, similar to a meniscus shape. This can collect light from a larger field of view into the optical lens, reducing the field of view of the subsequent lens. The sixth lens 600 has negative optical power, which helps increase the angle of incidence of light reaching the photosensitive chip 700, thereby effectively improving the relative illumination and increasing the image surface. Each lens meets the above conditional formula and works together to correct the aberration of the main light. The magnification is basically the same in different fields of view, and the distortion can be controlled within a range of 0.6%, ensuring the similarity between the object and the image.

[0026] It is understood 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 formulas: 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 .

[0027] It should be understood that the refractive index refers to the refractive index value of optical glass at standard temperature (20°C) and standard wavelength (587.56nm). In some embodiments, the second lens element 200 and the fourth lens element 400 are both made of high-refractive-index materials and have positive optical power, effectively reducing their own spherical aberration and coma. The fourth lens element 400 has a convex surface facing the object side and a concave surface facing the image side, also similar to a meniscus shape. The combination of high-refractive-index materials helps reduce its own field curvature.

[0028] It is understood 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 formulas: 55<Vd1<65, 50<Vd2<60, 30<Vd3<40, 30<Vd4<40, 75<Vd5<85, 30<Vd6<40, in, Vd1 is the Abbe coefficient of the first lens 100 , Vd2 is the Abbe coefficient of the second lens 200 , Vd3 is the Abbe coefficient of the third lens 300 , Vd4 is the Abbe coefficient of the fourth lens 400 , Vd5 is the Abbe coefficient of the fifth lens 500 , and Vd6 is the Abbe coefficient of the sixth lens 600 .

[0029] The dispersion coefficients of the lenses satisfy the above-mentioned conditional formula, and the dispersion coefficients are matched with each other, which is beneficial to eliminating the chromatic aberration of the optical lens and providing high-resolution color images.

[0030] It is understood that a 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 formulas: 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 distance between the first lens 100 and the second lens 200, A02 is the air distance between the second lens 200 and the third lens 300, A03 is the air distance between the third lens 300 and the fourth lens 400, AS1 is the air distance between the fourth lens 400 and the aperture 800, AS2 is the air distance between the aperture 800 and the fifth lens 500, A05 is the air distance between the fifth lens 500 and the sixth lens 600, BF is the back focus of the optical lens, and TL is the overall length of the optical lens.

[0031] Example 1: The focal length F of the optical lens is 25mm, F / NO=5.6, the actual imaging target surface is φ29, and the total length TL of the optical lens is 49mm. The surface of the first lens 100 facing the object side is convex, and the surface of the first lens 100 facing the image side is concave. The second lens 200 has both convex surfaces, and the curvature of the surface of the second lens 200 facing the object side is greater than the curvature of the surface of the second lens 200 facing the image side. The third lens 300 has both concave surfaces, and the curvature of the surface of the third lens 300 facing the object side is less than the curvature of the surface of the third lens 300 facing the image side. The fourth lens 400 has a convex surface facing the object side, and the surface of the fourth lens 400 facing the image side is concave. The fifth lens 500 has both convex surfaces, and the curvature of the surface of the fifth lens 500 facing the object side is greater than the curvature of the surface of the fifth lens 500 facing the image side. The sixth lens 600 has a concave surface facing the object side, and the surface of the sixth lens 600 facing the image side is convex. A protective glass 900 with a thickness of 2.5 mm is placed between the sixth lens 600 and the photosensitive chip 700. A stop 800 is placed between the fourth lens 400 and the fifth lens 500. The specific parameters of the optical lens are shown in Table 1, where the surfaces are numbered sequentially from the object side to the image side along the optical axis 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.

[0032] Table 1 Parameters of the optical lens of Example 1

[0033] In Table 1, "Infinity" refers to infinity. The optical performance of the optical lens implemented in 1 was tested, and the results are shown in the figure. Figure 2 The MTF curve of the optical lens of Example 1 is used to evaluate the resolving power of the optical lens. As can be seen from the illustrated curve, the MTF curves under each field of view are relatively concentrated without large dispersion, proving that various aberrations are well corrected and the consistency of each field of view is good. Figure 3This is the diffusion pattern of the optical lens of Example 1. From the results shown in the figure, it can be seen that the convergence of light in each field of view is very concentrated, close to the diffraction limit, which proves that the optical lens has a good imaging effect. Figure 4 1 is the field curvature and distortion curve of the optical lens of Example 1. From the results shown in the figure, it can be seen that the distortion is controlled below 0.6%. Figure 5 This is a relative illumination diagram of the optical lens of Example 1. The relative illumination of the edge field of view of the optical lens can reach more than 68%.

[0034] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the scope of the present invention.

Claims

1. A 25mm half-frame aerial photography 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 sequentially arranged along the optical axis from the object side to the image side; The first lens (100) has a negative optical focal power, the second lens (200) has a positive optical focal power, the third lens (300) has a negative optical focal power, the fourth lens (400) has a positive optical focal power, the fifth lens (500) has a positive optical focal power, and the sixth lens (600) has a negative optical focal 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 optical lens.

2. The 25mm half-frame aerial photography 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 half-frame aerial photography lens according to claim 1, characterized in that: The surface of the first lens (100) facing the object side is a convex surface, and the surface of the first lens (100) facing the image side is a concave surface.

4. The 25mm half-frame aerial photography lens according to claim 1, characterized in that: Both side surfaces of the second lens (200) are convex surfaces, and the curvature of the side of the second lens (200) facing the object side is greater than the curvature of the side of the second lens (200) facing the image side.

5. The 25mm half-frame aerial photography lens according to claim 1, characterized in that: Both side surfaces of the third lens (300) are concave surfaces, and the curvature of the side of the third lens (300) facing the object side is smaller than the curvature of the side of the third lens (300) facing the image side.

6. The 25mm half-frame aerial photography lens according to claim 1, characterized in that: The surface of the fourth lens (400) facing the object side is a convex surface, and the surface of the fourth lens (400) facing the image side is a concave surface.

7. The 25mm half-frame aerial photography lens according to claim 1, characterized in that: Both side surfaces of the fifth lens (500) are convex surfaces, and the curvature of the side of the fifth lens (500) facing the object side is greater than the curvature of the side of the fifth lens (500) facing the image side.

8. The 25mm half-frame aerial photography lens according to claim 1, characterized in that: The surface of the sixth lens (600) facing the object side is a concave surface, and the surface of the sixth lens (600) facing the image side is a convex surface.

9. The 25mm half-frame aerial photography 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 half-frame aerial photography lens according to claim 1, characterized in that: An aperture (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: 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 spacing distance between the first lens (100) and the second lens (200), A02 is the air spacing distance between the second lens (200) and the third lens (300), A03 is the air spacing distance between the third lens (300) and the fourth lens (400), AS1 is the air spacing distance between the fourth lens (400) and the aperture (800), AS2 is the air spacing distance between the aperture (800) and the fifth lens (500), A05 is the air spacing distance between the fifth lens (500) and the sixth lens (600), BF is the back focus of the optical lens, and TL is the overall length of the optical lens.

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