Telescope optical system and telescope

Abstract

The invention discloses a telescopic optical system, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged from an object side to an image side, the first lens has positive focal power, the second lens has negative focal power, the third lens has negative focal power, the fourth lens has positive focal power, the fifth lens has positive focal power, the sixth lens has positive focal power, and the seventh lens has negative focal power. According to the telescopic optical system, lens combinations of different structures are arranged, the focal power of each lens is reasonably distributed, under the condition that the magnification of the telescopic optical system is guaranteed, the overall size of the system is reduced, the total weight of the system is reduced, miniaturization of finished equipment is facilitated, carrying is convenient, meanwhile, the production and manufacturing cost can be reduced, and application and popularization are facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and in particular to a telescopic optical system and a telescope. Background Art

[0002] Traditional telescopes are large in size and heavy in weight, which makes them inconvenient to use for long periods of time. The standard magnification of mainstream telescopes on the market is 6 to 12 times, which is too small to meet the needs of viewing small targets at longer distances, such as the stars and birds. If a larger magnification is required, the size of the system will be significantly larger, and the weight will also increase significantly. In addition, in order to ensure the magnification and image quality, the existing products on the market use a large number of lenses, and some even use aspherical lenses, which are costly and expensive. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a telescopic optical system with high magnification, small system size and low manufacturing cost.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a telescopic optical system, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence from the object side to the image side; the first lens has a positive optical focal power, the second lens has a negative optical focal power, the third lens has a negative optical focal power, the fourth lens has a positive optical focal power, the fifth lens has a positive optical focal power, the sixth lens has a positive optical focal power, and the seventh lens has a negative optical focal power.

[0005] The beneficial effects of the present invention are as follows: the telescopic optical system reduces the overall size of the system and the total weight of the system by arranging lens combinations of different structures and reasonably distributing the optical focal length of each lens while ensuring the magnification of the telescopic optical system, which is conducive to the miniaturization of the finished device and convenient carrying. At the same time, it can reduce the production cost and is conducive to popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 Schematic diagram of the structure of the telescopic optical system according to the first embodiment of the present invention; Figure 2 Schematic diagram of surface numbering of a telescopic optical system according to Embodiment 1 of the present invention; Figure 3 The MTF curve diagram of an ideal lens with a focal length of 5 mm set at the exit pupil position of the telescopic optical system of the first embodiment of the present invention; Figure 4 This is a curve diagram showing the change of the MTF value of the telescopic optical system at a specific spatial frequency as a function of the field of view according to the first embodiment of the present invention; Figure 5This is a dispersion pattern of the telescopic optical system in the afocal mode according to the first embodiment of the present invention.

[0007] Description of labels: 1. The first lens; 2. Second lens; 3. The third lens; 4. The fourth lens; 5. The fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Aperture; 9. Dove prism; 10. Right angle prism; 11. Neutral density filter. DETAILED DESCRIPTION

[0008] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0009] Please refer to Figures 1 to 5 , a telephoto optical system, comprising a first lens 1, a second lens 2, an aperture 8, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6 and a seventh lens 7 arranged in sequence from the object side to the image side; the first lens 1 has positive focal power, the second lens 2 has negative focal power, the third lens 3 has negative focal power, the fourth lens 4 has positive focal power, the fifth lens 5 has positive focal power, the sixth lens 6 has positive focal power, and the seventh lens 7 has negative focal power.

[0010] The beneficial effects of the present invention are as follows: the telescopic optical system reduces the overall size of the system and the total weight of the system by arranging lens combinations of different structures and reasonably distributing the optical focal length of each lens while ensuring the magnification of the telescopic optical system, which is conducive to the miniaturization of the finished device and convenient carrying. At the same time, it can reduce the production cost and is conducive to popularization and use.

[0011] Furthermore, the object side surface and the image side surface of the first lens 1 are both convex surfaces; the object side surface of the second lens 2 is a concave surface, and the image side surface of the second lens 2 is a plane; the object side surface of the third lens 3 is a plane, and the image side surface of the third lens 3 is a concave surface; the object side surface and the image side surface of the fourth lens 4 are both convex surfaces; the object side surface of the fifth lens 5 is a convex surface, and the image side surface of the fifth lens 5 is a concave surface; the object side surface and the image side surface of the sixth lens 6 are both convex surfaces; and the object side surface and the image side surface of the seventh lens 7 are both concave surfaces.

[0012] Furthermore, a dove prism 9 is provided between the second lens 2 and the aperture 8, and a right-angle prism 10 is provided between the aperture 8 and the third lens 3; the second lens 2, the dove prism 9, the aperture 8, the right-angle prism 10 and the third lens 3 satisfy: 0.6 28 / TL<0.8,0.03 83 / TL<0.07, where A 28 is the sum of the air distance between the second lens 2 and the aperture 8 and the equivalent thickness of the Dove prism 9, TL is the overall length of the telescopic optical system, and A 83 It is the sum of the air distance between the aperture 8 and the third lens 3 and the equivalent thickness of the right-angle prism 10.

[0013] As can be seen from the above description, the dove prism 9 and the right-angle prism 10 can change the direction of the optical path, which is conducive to adapting the telescopic optical system to the internal space of the finished device or reducing the overall length of the finished device. The aperture 8 is located at a reasonable ratio between the second lens 2 and the third lens 3 to ensure the magnification of the telescopic optical system.

[0014] Further, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 satisfy: f 1-2 >200; 0 <f 3-7 <20; 0.5 <f 3-5 / f 3-7 <2; -6 <f 6-7 / f 3-7 <-2; 1 <TL / f 1-2 <1.5; where f 1-2 is the combined focal length of the first lens 1 and the second lens 2, f 3-7 is the combined focal length of the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7, 3-5 is the combined focal length of the third lens 3, the fourth lens 4 and the fifth lens 5, f 6-7 is the combined focal length of the sixth lens 6 and the seventh lens 7, and TL is the overall length of the telescopic optical system.

[0015] ​​As can be seen from the above description, the magnification of the system is guaranteed by controlling the focal length of the objective lens and the eyepiece. The first lens 1 and the second lens 2 are combined to form an objective lens, which can collect object light and converge it inside the optical system to form an intermediate image. The third lens 3, the fourth lens 4 and the fifth lens 5 are combined to form an eyepiece. The combined focal length is relatively small, and the light of the intermediate image can be quickly converged in a smaller space, which is conducive to reducing the size of the system and realizing the miniaturization of the system appearance.

[0016] Furthermore, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the sixth lens 6 and the seventh lens 7 satisfy: |Nd1-Nd2|>0.15; Nd3>1.7; Nd4>1.7; |Nd6-Nd7|>0.2; Wherein Nd1 is the refractive index of the first lens 1 , Nd2 is the refractive index of the second lens 2 , Nd3 is the refractive index of the third lens 3 , Nd4 is the refractive index of the fourth lens 4 , Nd6 is the refractive index of the sixth lens 6 , and Nd7 is the refractive index of the seventh lens 7 .

[0017] From the above description, it can be seen that each lens is made of a material with a reasonable refractive index, especially the third lens 3 and the fourth lens 4 are made of a high refractive index material, so as to converge the light of the intermediate image plane in a smaller space, which is conducive to miniaturization of the system appearance.

[0018] Furthermore, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the sixth lens 6 and the seventh lens 7 satisfy: |Vd1-Vd2|>20; Vd3<50; Vd4<50; |Vd6-Vd7|>25; Wherein Vd1 is the dispersion coefficient of the first lens 1 , Vd2 is the dispersion coefficient of the second lens 2 , Vd3 is the dispersion coefficient of the third lens 3 , Vd4 is the dispersion coefficient of the fourth lens 4 , Vd6 is the dispersion coefficient of the sixth lens 6 , and Vd7 is the dispersion coefficient of the seventh lens 7 .

[0019] It can be seen from the above description that each lens is made of a material with a reasonable dispersion coefficient, especially the high and low dispersion coefficients of the first lens 1 and the second lens 2 are matched with each other, and the high and low dispersion coefficients of the sixth lens 6 and the seventh lens 7 are matched with each other, which is beneficial to eliminating system chromatic aberration and ensuring the imaging effect at a large magnification.

[0020] Furthermore, it also includes a neutral density filter 11 , which is arranged on the object side of the first lens 1 .

[0021] It can be seen from the above description that under strong light conditions, the neutral density filter 11 can attenuate the light entering the optical system to avoid overexposure when viewing the picture.

[0022] Furthermore, the aperture FNO of the telephoto optical system is 12.5.

[0023] From the above description, it can be seen that a sufficiently large aperture can allow sufficient light to enter the system, and a high-definition image can still be obtained at a large magnification.

[0024] The telescope comprises a lens barrel and the above-mentioned telescopic optical system, wherein the telescopic optical system is installed in the lens barrel.

[0025] From the above description, it can be seen that the telescope has a high magnification, a small system size and a low manufacturing cost.

[0026] Please refer to Figures 1 to 5 , Embodiment 1 of the present invention is: a telescope, comprising a lens barrel and a telescopic optical system, wherein the telescopic optical system is installed in the lens barrel.

[0027] The telescopic optical system includes a first lens 1, a second lens 2, an aperture 8, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6 and a seventh lens 7 which are arranged in sequence from the object side to the image side; the first lens 1 has positive focal power, the second lens 2 has negative focal power, the third lens 3 has negative focal power, the fourth lens 4 has positive focal power, the fifth lens 5 has positive focal power, the sixth lens 6 has positive focal power, and the seventh lens 7 has negative focal power.

[0028] Specifically, the first lens 1 and the second lens 2 are combined to form an objective lens, and the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 are combined to form an eyepiece. In this embodiment, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 are all glass spherical lenses. The object side and the image side of the first lens 1 are both convex; the object side of the second lens 2 is a concave surface, and the image side of the second lens 2 is a plane; the object side of the third lens 3 is a plane, and the image side of the third lens 3 is a concave surface; the object side and the image side of the fourth lens 4 are both convex surfaces; the object side of the fifth lens 5 is a convex surface, and the image side of the fifth lens 5 is a concave surface; the object side and the image side of the sixth lens 6 are both convex surfaces; the object side and the image side of the seventh lens 7 are both concave surfaces. The first lens 1 and the second lens 2 are glued together, and the sixth lens 6 and the seventh lens 7 are glued together.

[0029] A dove prism 9 is also provided between the second lens 2 and the aperture 8, and a right-angle prism 10 is also provided between the aperture 8 and the third lens 3. In this embodiment, the dove prism 9 and the right-angle prism 10 are both made of glass. The first lens 1 and the second lens 2 are coaxially arranged, and the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 are coaxially arranged, and the axial directions of the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 are perpendicular to the circumferential directions of the first lens 1 and the second lens 2. The dove prism 9 and the right-angle prism 10 can change the direction of the optical path, which is conducive to adapting the telescopic optical system to the internal space of the finished device, or reducing the overall length of the finished device.

[0030] The second lens 2, the dove prism 9, the aperture 8, the right angle prism 10 and the third lens 3 meet the following requirements: 0.6 28 / TL<0.8,0.03 83 / TL<0.07, where A 28 is the sum of the air distance between the second lens 2 and the aperture 8 and the equivalent thickness of the Dove prism 9, TL is the overall length of the telephoto optical system, A 83 It is the sum of the air distance between the aperture 8 and the third lens 3 and the equivalent thickness of the right-angle prism 10.

[0031] The first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 satisfy the following requirements: f 1-2 >200; 0 <f 3-7 <20; 0.5 <f 3-5 / f 3-7 <2; -6 <f 6-7 / f 3-7 <-2; 1 <TL / f 1-2 <1.5; where f 1-2 is the combined focal length of the first lens 1 and the second lens 2, f 3-7 is the combined focal length of the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7, f 3-5 is the combined focal length of the third lens 3, the fourth lens 4 and the fifth lens 5, f 6-7 is the combined focal length of the sixth lens 6 and the seventh lens 7, and TL is the overall length of the telephoto optical system.

[0032] The first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the sixth lens 6 and the seventh lens 7 satisfy: |Nd1-Nd2|>0.15; ​​Nd3>1.7; Nd4>1.7; |Nd6-Nd7|>0.2; Wherein Nd1 is the refractive index of the first lens 1 , Nd2 is the refractive index of the second lens 2 , Nd3 is the refractive index of the third lens 3 , Nd4 is the refractive index of the fourth lens 4 , Nd6 is the refractive index of the sixth lens 6 , and Nd7 is the refractive index of the seventh lens 7 .

[0033] The first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the sixth lens 6 and the seventh lens 7 satisfy: |Vd1-Vd2|>20; Vd3<50; Vd4<50; |Vd6-Vd7|>25; Wherein Vd1 is the dispersion coefficient of the first lens 1 , Vd2 is the dispersion coefficient of the second lens 2 , Vd3 is the dispersion coefficient of the third lens 3 , Vd4 is the dispersion coefficient of the fourth lens 4 , Vd6 is the dispersion coefficient of the sixth lens 6 , and Vd7 is the dispersion coefficient of the seventh lens 7 .

[0034] The telephoto optical system further includes a neutral density filter 11 , which is disposed on the object side of the first lens 1 .

[0035] In this embodiment, the objective lens focal length of the telescopic optical system, that is, the combined focal length of the first lens 1 and the second lens 2 is f 1-2 =360mm; the eyepiece focal length of the telescopic optical system, i.e., the combined focal length f of the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6 and the seventh lens 7 3-7 =15mm; telephoto optical system aperture FNO=12.5; total length of the telephoto optical system TL=428.7mm, magnification 24X, field of view angle 1.92°.

[0036] The specific parameters of each lens in the telescopic optical system of the first embodiment are shown in Table 1 below ( Figure 2 Schematic diagram of surface numbering of the telescopic optical system according to the first embodiment of the present invention): Table 1:

[0037] Figure 3 , Figure 4 and Figure 5 is an optical performance chart of the telescopic optical system in this embodiment, wherein Figure 3The MTF curve of an ideal lens with a focal length of 5mm set at the exit pupil position can be used to evaluate the resolution of the optical system. From the curve in the figure, it can be seen that each MTF curve is close to the diffraction limit, indicating that the aberrations of the system have been well corrected; Figure 4 The MTF value of the telescopic optical system according to the first embodiment of the present invention at a specific spatial frequency varies with the field of view. The difference in the MTF value of each field of view is very small, indicating that the uniformity of the optical performance of each field of view of the system is very good, and the difference between the inside and outside is very small; Figure 5 This is a dispersion pattern diagram of the telescopic optical system in the afocal mode according to the first embodiment of the present invention. It can be seen from the figure that the dispersion pattern of each field of view is very small, and the RMS radius is much smaller than 3 arcmin, which further illustrates that a good imaging effect has been obtained through the telescopic optical system.

[0038] In summary, the telescopic optical system provided by the present invention reasonably distributes the optical focal length of each lens by arranging a combination of lenses with different structures. Under the condition of ensuring the magnification of the telescopic optical system, the overall size of the system is reduced, the total weight of the system is reduced, which is conducive to the miniaturization of the finished equipment and convenient carrying. At the same time, it can reduce the production cost and is conducive to popularization and use.

[0039] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A telescopic optical system, characterized in that: The invention comprises a first lens, a second lens, an aperture, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are arranged in sequence from the object side to the image side; the first lens has positive focal power, the second lens has negative focal power, the third lens has negative focal power, the fourth lens has positive focal power, the fifth lens has positive focal power, the sixth lens has positive focal power, and the seventh lens has negative focal power.

2. The telescopic optical system according to claim 1, characterized in that: The object side surface and the image side surface of the first lens are both convex surfaces; the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a plane; the object side surface of the third lens is a plane, and the image side surface of the third lens is a concave surface; the object side surface and the image side surface of the fourth lens are both convex surfaces; the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a concave surface; the object side surface and the image side surface of the sixth lens are both convex surfaces; and the object side surface and the image side surface of the seventh lens are both concave surfaces.

3. The telescopic optical system according to claim 1, characterized in that: A dove prism is also provided between the second lens and the aperture, and a right-angle prism is also provided between the aperture and the third lens; the second lens, the dove prism, the aperture, the right-angle prism and the third lens satisfy: 0.6 28 / TL<0.8,0.03 83 / TL<0.07, where A 28 is the sum of the air distance between the second lens and the aperture and the equivalent thickness of the Dove prism, TL is the overall length of the telescopic optical system, and A 83 It is the sum of the air distance between the aperture and the third lens and the equivalent thickness of the right-angle prism.​​ 4. The telescopic optical system according to claim 1, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens satisfy: f 1-2 >200； 0<f 3-7 <20； 0.5<f 3-5 / f 3-7 <2; -6<f 6-7 / f 3-7 <-2; 1<TL / f 1-2 <1.5; where f 1-2 is the combined focal length of the first lens and the second lens, f 3-7 is the combined focal length of the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens, f 3-5 is the combined focal length of the third lens, the fourth lens and the fifth lens, f 6-7 is the combined focal length of the sixth lens and the seventh lens, and TL is the overall length of the telephoto optical system.

5. The telescopic optical system according to claim 1, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the sixth lens and the seventh lens satisfy: |Nd1-Nd2|>0.15; Nd3>1.7; Nd4>1.7; |Nd6-Nd7|>0.2; Wherein 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, Nd6 is the refractive index of the sixth lens, and Nd7 is the refractive index of the seventh lens.

6. The telescopic optical system according to claim 1, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the sixth lens and the seventh lens satisfy: |Vd1-Vd2|>20; Vd3<50; Vd4<50; |Vd6-Vd7|>25; Wherein 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, Vd6 is the dispersion coefficient of the sixth lens, and Vd7 is the dispersion coefficient of the seventh lens.

7. The telescopic optical system according to claim 1, characterized in that: A neutral density filter is also included, and the neutral density filter is arranged on the object side of the first lens.

8. The telescopic optical system according to claim 1, characterized in that: The aperture FNO of the telephoto optical system is 12.

5.

9. A telescope, characterized in that The invention comprises a lens barrel and a telescopic optical system as claimed in any one of claims 1 to 8, wherein the telescopic optical system is installed in the lens barrel.

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