Telephoto lens

Abstract

The utility model belongs to the technical field of optical imaging systems, and particularly relates to a telephoto lens. The optical system comprises a first lens, a second lens, a diaphragm, a third lens, a fourth lens, a fifth lens, a sixth lens, an optical filter and an imaging surface which are sequentially arranged from an object side to an image side. The first lens has positive focal power, an object side surface is a convex surface, and an image side surface is a concave surface; the second lens has negative focal power, and the object side surface and the image side surface are concave surfaces; the third lens has positive focal power, the object side surface is a concave surface, and the image side surface is a convex surface; the fourth lens has positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface; the fifth lens has negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface; the sixth lens has negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface. Wherein the fourth lens and the fifth lens are bonded to form a bonding lens, and the lenses are made of glass materials. Through reasonable design, the telephoto lens provided by the utility model has the advantages of simple structure, low cost, small distortion, large target surface, high imaging quality and high overall reliability.

Description

Technical Field

[0001] The utility model belongs to the technical field of optical imaging systems, and particularly relates to a long-focus lens. Background Art

[0002] In recent years, with the rapid development of optoelectronic technology, the requirements for optical lenses have become increasingly high. In vehicle-mounted lenses, forward collision warning not only requires photographing objects at a long distance in harsh environments, but also requires an imaging chip to be larger and the volume to be smaller, while requiring small distortion to reduce imaging deformation. Therefore, there is a demand in the current market for a lens with a large target surface, small distortion, good overall reliability, and excellent imaging quality. Summary of the Utility Model

[0003] To solve the defects and deficiencies of the prior art, the purpose of the utility model is to provide an optical lens with a simple structure, low cost, small distortion, large target surface, high imaging quality, and high overall reliability.

[0004] To achieve the above purpose, the technical solution adopted by the utility model is: it includes a first lens, a second lens, a diaphragm, a third lens, a fourth lens, a fifth lens, a sixth lens, a filter, and an imaging surface. The first lens has a positive optical power, the object side is convex, and the image side is concave; the second lens has a negative optical power, and both the object side and the image side are concave; the third lens has a positive optical power, the object side is concave, and the image side is convex; the fourth lens has a positive optical power, the object side is convex, and the image side is concave; the fifth lens has a negative optical power, the object side is convex, and the image side is concave; the sixth lens has a negative optical power, the object side is convex, and the image side is concave. Among them, the fourth lens and the fifth lens are bonded into a cemented lens, and the lenses are all made of glass materials.

[0005] Preferably, the first lens also satisfies: N1≥1.79, V1≤44.2, where N1 is the refractive index of the first lens and V1 is the Abbe number of the first lens;

[0006] The second lens also satisfies: N2≥1.75, V2≤27.7, where N2 is the refractive index of the second lens and V2 is the Abbe number of the second lens;

[0007] The third lens also satisfies: N3≥1.8, V3≤45.5, where N3 is the refractive index of the third lens and V3 is the Abbe number of the third lens;

[0008] The fourth lens also satisfies: N4≥1.9, V4≤31.3, where N4 is the refractive index of the fourth lens and V4 is the Abbe number of the fourth lens.

[0009] The fifth lens also satisfies: N5≥1.71, V5≤53.8, where N5 is the refractive index of the fifth lens and V5 is the Abbe number of the fifth lens.

[0010] The sixth lens also satisfies: N6≥1.66, V6≤57.4, where N6 is the refractive index of the sixth lens and V6 is the Abbe number of the sixth lens.

[0011] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical lenses made of glass.

[0012] Preferably, the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are f1, f2, f3, f4, f5, and f6 respectively, and the focal length of the overall optical system is f, which satisfies the following ratio: 1.2 < f1 / f < 1.4, -0.9 < f2 / f < -0.7, 1.2 < f3 / f < 1.4, 1.5 < f4 / f < 1.7, -2.2 < f5 / f < -2.0, -8.5 < f6 / f < -8.2.

[0013] Preferably, the air gap between the first lens and the second lens is 2.1 to 2.8 mm, the air gap between the second lens and the diaphragm is 1.8 to 2.1 mm, the air gap between the diaphragm and the third lens is 0.6 to 0.9 mm, the air gap between the third lens and the fourth lens is 0.3 to 0.5 mm, the air gap between the fifth lens and the sixth lens is 0.6 to 0.8 mm, and the air gap between the sixth lens and the filter is 2.4 to 2.6 mm.

[0014] Preferably, for the focal length EFL of the optical system and the total optical length TOTR of the optical system, it also satisfies: 0.4 ≤ EFL / TOTR ≤ 0.6.

[0015] Preferably, the diaphragm of the optical system is located between the second lens and the third lens.

[0016] Preferably, the filter of the optical system is located between the sixth lens and the imaging surface.

[0017] After adopting the above structure, the beneficial effects of the present utility model are as follows:

[0018] 1. It adopts a design of six spherical lenses made of all glass, with a simple structure, greatly reducing the manufacturing cost and processing difficulty, facilitating mass production. The all-glass lens design can adapt to different environments, and the overall reliability is high.

[0019] 2. Through optimized design and reasonable distribution of the optical power, it realizes the characteristics of small distortion, large target surface, high imaging quality, and high overall reliability.

[0020] 3. Large target surface, which can be used to match the photosensitive chip with the largest 1 / 1.8" large target surface. Brief Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be described in detail by the following specific embodiments and the accompanying drawings.

[0022] Figure 1 is the structural schematic diagram of the present invention;

[0023] Figure 2 is the modulation transfer function curve diagram of the present invention.

[0024] Figure 3 is the field curvature distortion diagram of the present invention

[0025] Figure 4 is the spot diagram of the present invention

[0026] Figure 5 is the lateral chromatic aberration diagram of the present invention

[0027] Explanation of reference numerals: L1 - the first lens, L2 - the second lens, L3 - the third lens, L4 - the fourth lens, L5 - the fifth lens, L6 - the sixth lens, L7 - the filter, S - the aperture. IMA - the imaging surface Detailed Description of the Embodiments

[0028] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described below through specific embodiments shown in the drawings. However, it should be understood that these descriptions are only exemplary and do not limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0029] Here, it should also be noted that in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, and other details less related to the present invention are omitted.

[0030] Refer to, for example Figure 1As shown in the figure, the present specific embodiment adopts the following technical solution: The optical system includes a first lens, a second lens, a diaphragm, a third lens, a fourth lens, a fifth lens, a sixth lens, a filter, and an imaging surface arranged in sequence from the object side to the image side. The first lens has a positive optical power, the object side is convex, and the image side is concave; the second lens has a negative optical power, and both the object side and the image side are concave; the third lens has a positive optical power, the object side is concave, and the image side is convex; the fourth lens has a positive optical power, the object side is convex, and the image side is concave; the fifth lens has a negative optical power, the object side is convex, and the image side is concave; the sixth lens has a negative optical power, the object side is convex, and the image side is concave. Among them, the fourth lens and the fifth lens are bonded into a cemented lens, and all the lenses are made of glass materials.

[0031] In this embodiment, the first lens further satisfies: N1≥1.79, V1≤44.2, where N1 is the refractive index of the first lens and V1 is the Abbe number of the first lens;

[0032] The second lens further satisfies: N2≥1.75, V2≤27.7, where N2 is the refractive index of the second lens and V2 is the Abbe number of the second lens;

[0033] The third lens further satisfies: N3≥1.8, V3≤45.5, where N3 is the refractive index of the third lens and V3 is the Abbe number of the third lens;

[0034] The fourth lens further satisfies: N4≥1.9, V4≤31.3, where N4 is the refractive index of the fourth lens and V4 is the Abbe number of the fourth lens.

[0035] The fifth lens further satisfies: N5≥1.71, V5≤53.8, where N5 is the refractive index of the fifth lens and V5 is the Abbe number of the fifth lens.

[0036] The sixth lens further satisfies: N6≥1.66, V6≤57.4, where N6 is the refractive index of the sixth lens and V6 is the Abbe number of the sixth lens.

[0037] In this embodiment, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical lenses made of glass.

[0038] In this embodiment, the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are f1, f2, f3, f4, f5, and f6 respectively, and the focal length of the overall optical system is f, which satisfies the following ratio: 1.2 < f1 / f < 1.4, -0.9 < f2 / f < -0.7, 1.2 < f3 / f < 1.4, 1.5 < f4 / f < 1.7, -2.2 < f5 / f < -2.0, -8.5 < f6 / f < -8.2.

[0039] In this embodiment, the air gap between the first lens and the second lens is 2.1 to 2.8 mm, the air gap between the second lens and the diaphragm is 1.8 to 2.1 mm, the air gap between the diaphragm and the third lens is 0.6 to 0.9 mm, the air gap between the third lens and the fourth lens is 0.3 to 0.5 mm, the air gap between the fifth lens and the sixth lens is 0.6 to 0.8 mm, and the air gap between the sixth lens and the filter is 2.4 to 2.6 mm.

[0040] In this embodiment, the focal length EFL of the optical system and the total optical length TOTR of the optical system further satisfy: 0.4 ≤ EFL / TOTR ≤ 0.6.

[0041] In this embodiment, the diaphragm of the optical system is located between the second lens and the third lens.

[0042] In this embodiment, the filter of the optical system is located between the sixth lens and the imaging surface.

[0043] In the embodiment of the present application, for convenience of description, the following expressions are made: the object surface is OBJ, the front surface of the first lens is S1, the rear surface of the first lens is S2, the front surface of the second lens is S3, the rear surface of the second lens is S4, the front surface of the third lens is S5, the rear surface of the third lens is S6, the diaphragm is STO, the front surface of the fourth lens is S7, the rear surface of the fourth lens and the front surface of the fifth lens are S8, the rear surface of the fifth lens is S9, the front surface of the sixth lens is S10, the rear surface of the sixth lens is S11, the front surface of the filter is S12, the rear surface of the filter is S13, and the imaging surface is IMA. The parameters of each lens are as follows in the table:

[0044]

[0045] In this embodiment, the optical lens achieves the following technical indicators:

[0046] ① Focal length: EFFL = 15.56 mm; ② Aperture FNO = 1.8; ③ Field of view: F0V ≥ 30°; ④ Distortion: < 0.32%; ⑤ Imaging circle diameter ≤ φ8.2; ⑥ Total optical length TOTR ≤ 28 mm.

[0047] Figure 2 This is the modulation transfer function curve graph of the telephoto lens in this embodiment. It can be seen from the figure that the MTF of the optical lens performs well in the visible light band. At the spatial frequency of 70 LP / MM in the central field of view, its MTF value is greater than 0.65; at the spatial frequency of 70 LP / MM in the marginal field of view, its MTF value is greater than 0.6. It can be seen that the curve drops gently and concentratedly, indicating that the various performance of this optical lens is good.

[0048] Figure 3 This is the field curvature and distortion diagram of the telephoto lens in this embodiment. It can be seen from the figure that the maximum optical distortion value of the optical lens in the full field of view is less than 0.32%, which ensures the authenticity of the picture and reduces the distortion of the picture. The field curvature of the optical lens for light of different wavelengths is effectively controlled within ±0.1 mm, that is, the difference between the central image quality and the peripheral image quality during imaging is small.

[0049] Figure 4 This is the spot diagram of the telephoto lens in this embodiment. It can be seen from the figure that the spot sizes of each wavelength in different fields of view, and the maximum RSM radius is 3.827 um, indicating that the aberrations of this optical system are small and the imaging quality is good.

[0050] Figure 5 This is the lateral chromatic aberration diagram of the telephoto lens in this embodiment. It can be seen from the figure that the chromatic aberrations of each wavelength are within the Airy disk range, indicating that the chromatic aberrations of each wavelength are corrected well, effectively improving the image quality.

[0051] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

[0052] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A telephoto lens, characterized in that: It includes a first lens, a second lens, a diaphragm, a third lens, a fourth lens, a fifth lens, a sixth lens, a filter, and an imaging surface arranged in sequence from the object side to the image side. The first lens has a positive optical power, with the object side being convex and the image side being concave; the second lens has a negative optical power, and both the object side and the image side are concave; the third lens has a positive optical power, with the object side being concave and the image side being convex; the fourth lens has a positive optical power, with the object side being convex and the image side being concave; the fifth lens has a negative optical power, with the object side being convex and the image side being concave; the sixth lens has a negative optical power, with the object side being convex and the image side being concave. Among them, the fourth lens and the fifth lens are bonded together as a cemented lens, and all the lenses are made of glass materials.

2. The telephoto lens according to claim 1, wherein: The first lens further satisfies: N1≥1.79, V1≤44.2, where N1 is the refractive index of the first lens and V1 is the Abbe number of the first lens; The second lens further satisfies: N2≥1.75, V2≤27.7, where N2 is the refractive index of the second lens and V2 is the Abbe number of the second lens; The third lens further satisfies: N3≥1.8, V3≤45.5, where N3 is the refractive index of the third lens and V3 is the Abbe number of the third lens; The fourth lens further satisfies: N4≥1.9, V4≤31.3, where N4 is the refractive index of the fourth lens and V4 is the Abbe number of the fourth lens; The fifth lens further satisfies: N5≥1.71, V5≤53.8, where N5 is the refractive index of the fifth lens and V5 is the Abbe number of the fifth lens; The sixth lens further satisfies: N6≥1.66, V6≤57.4, where N6 is the refractive index of the sixth lens and V6 is the Abbe number of the sixth lens.

3. A telephoto lens according to claim 1, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical lenses made of glass.

4. A telephoto lens according to claim 1, characterized in that: The focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are f1, f2, f3, f4, f5, and f6 respectively, and the focal length of the overall optical system is f, which satisfies the following ratios: 1.2 < f1 / f < 1.4, -0.9 < f2 / f < -0.7, 1.2 < f3 / f < 1.4, 1.5 < f4 / f < 1.7, -2.2 < f5 / f < -2.0, -8.5 < f6 / f < -8.

2.

5. A telephoto lens according to claim 1, characterized in that: The air gap between the first lens and the second lens is 2.1 - 2.8 mm, the air gap between the second lens and the diaphragm is 1.8 - 2.1 mm, the air gap between the diaphragm and the third lens is 0.6 - 0.9 mm, the air gap between the third lens and the fourth lens is 0.3 - 0.5 mm, the air gap between the fifth lens and the sixth lens is 0.6 - 0.8 mm, and the air gap between the sixth lens and the filter is 2.4 - 2.6 mm.

6. A telephoto lens according to claim 1, characterized in that: The diaphragm is located between the second lens and the third lens.

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