Large-aperture optical system
Through the structure of the four lenses and the optimized optical system, the problem of high cost of existing photography objective lenses is solved, and the imaging quality and low-cost production of large aperture F1.5 are achieved, which is suitable for the civil market.
Patent Information
- Application Number
- CN202422703555.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-06
- Publication Date
- 2025-08-19
- Estimated Expiration
- 2034-11-06
AI Technical Summary
Most of the existing photography objectives are small and medium aperture lenses. The use of more than 7 lenses or aspherical lenses leads to high development and use costs, making it difficult to popularize in the civil market.
The four-piece lens structure is adopted, including the first positive lens, the second negative lens, the third positive lens and the fourth positive lens. By optimizing the refractive index and Abbe number design, the spherical aberration, intelligent difference, astigmatism and chromatic aberration are corrected to achieve the imaging quality of large aperture F1.5.
It achieves good imaging quality within the maximum aperture F1.5 range, has a simple structure, low cost, and is suitable for mass production.
Smart Images
Figure CN223244884U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of optical systems, and in particular relates to a large aperture optical system. Background Art
[0002] Currently, most photographic objective lenses use the Cooke three-piece structure and its improved structure. Among these structures, most are small and medium aperture lenses, with a small number of F1.5 large aperture lens structures. Because they all use more than 7 lenses or aspherical lenses, the development and later use costs are high, making it difficult to popularize them in the civilian market. Utility Model Content
[0003] The present invention aims to solve the above technical problems at least to a certain extent. To this end, the present invention aims to provide a large aperture optical system.
[0004] The technical solution adopted by this utility model is:
[0005] A large aperture optical system comprises a first positive lens, a second negative lens, a third positive lens and a fourth positive lens arranged in sequence from the object side to the image side; the refractive index ND of the first positive lens is 1.56-1.66, and the Abbe number VD is 58-65; the refractive index ND of the second negative lens is 1.7-1.83, and the Abbe number VD is 23-33; the refractive index ND of the third positive lens is 1.56-1.66, and the Abbe number VD is 58-65; the refractive index ND of the fourth positive lens is 1.56-1.66, and the Abbe number VD is 58-65.
[0006] Preferably, the curvature radius of the first surface of the first positive lens is 16-19 mm, and the semi-clear aperture is 18-21 mm; the curvature radius of the second surface of the first positive lens is -500-500 mm, and the semi-clear aperture is 18-21 mm.
[0007] Preferably, the curvature radius of the first surface of the second negative lens is -15 to -13.5 mm, and the semi-clear aperture is 9 to 12 mm; the curvature radius of the second surface of the second negative lens is 20 to 22 mm, and the semi-clear aperture is 9 to 12 mm.
[0008] Preferably, the curvature radius of the first surface of the third positive lens is -500 to 500 mm, and the semi-clear aperture is 11 to 14 mm; the curvature radius of the second surface of the third positive lens is -12.5 to -14 mm, and the semi-clear aperture is 11 to 14 mm.
[0009] Preferably, the curvature radius of the first surface of the fourth positive lens is 14.5 to 16 mm, and the semi-clear aperture is 11 to 14 mm; the curvature radius of the second surface of the fourth positive lens is -500 to 500 mm, and the semi-clear aperture is 11 to 14 mm.
[0010] The beneficial effects of the utility model are:
[0011] The utility model provides a large aperture optical system, which uses four lenses to correct spherical aberration, coma, astigmatism and chromatic aberration, so that it has good image quality within the maximum aperture range of F1.5; the system structure is simple to assemble, low in cost, and suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 It is a schematic diagram of the large aperture optical system of the utility model.
[0013] Figure 2 It is a parameter diagram of the large aperture optical system of the utility model.
[0014] In the figure: 1-first positive lens; 2-second negative lens; 3-third positive lens; 4-fourth positive lens. DETAILED DESCRIPTION
[0015] Embodiments of the present invention are described in detail below, examples of which 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 to be used to explain the present invention and are not to be construed as limiting the present invention. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in a variety of different configurations.
[0016] In the present invention, unless otherwise clearly specified and limited, terms such as "installed", "connected", "connected", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two components.
[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0018] like Figure 1 and Figure 2As shown, a large aperture optical system of this embodiment uses four lenses to achieve an ultra-large aperture, a large field of view, and excellent imaging quality. It includes a first positive lens 1, a second negative lens 2, a third positive lens 3, and a fourth positive lens 4, arranged in sequence from the object side to the image side. A light beam from the object side passes through the first positive lens 1, the second negative lens 2, the third positive lens 3, and the fourth positive lens 4 in sequence to reach the image side, where an image is formed. The first positive lens 1 has a refractive index ND of 1.56 to 1.66 and an Abbe number VD of 58 to 65; the second negative lens 2 has a refractive index ND of 1.7 to 1.83 and an Abbe number VD of 23 to 33; the third positive lens 3 has a refractive index ND of 1.56 to 1.66 and an Abbe number VD of 58 to 65; and the fourth positive lens 4 has a refractive index ND of 1.56 to 1.66 and an Abbe number VD of 58 to 65.
[0019] like Figure 2 As shown, D1 is the thickness of the first positive lens 1, D2 is the air gap between the first positive lens 1 and the second negative lens 2, D3 is the thickness of the second negative lens 2, D4 is the air gap between the second negative lens 2 and the third positive lens 3, D5 is the thickness of the third positive lens 3, D6 is the air gap between the third positive lens 3 and the fourth positive lens 4, and D7 is the thickness of the fourth positive lens 4. R1 is the first surface of the first positive lens 1, R2 is the second surface of the first positive lens 1; R3 is the first surface of the second negative lens 2, R4 is the second surface of the second negative lens 2; R5 is the first surface of the third positive lens 3, R6 is the second surface of the third positive lens 3; R7 is the first surface of the fourth positive lens 4, and R8 is the second surface of the fourth positive lens 4.
[0020] Specifically, the radius of curvature of the first surface R1 of the first positive lens 1 is 16 to 19 mm, and the semi-clear aperture is 18 to 21 mm; the radius of curvature of the second surface R2 of the first positive lens 1 is -500 to 500 mm, and the semi-clear aperture is 18 to 21 mm. The radius of curvature of the first surface R3 of the second negative lens 2 is -15 to -13.5 mm, and the semi-clear aperture is 9 to 12 mm; the radius of curvature of the second surface R4 of the second negative lens 2 is 20 to 22 mm, and the semi-clear aperture is 9 to 12 mm. The radius of curvature of the first surface R5 of the third positive lens 3 is -500 to 500 mm, and the semi-clear aperture is 11 to 14 mm; the radius of curvature of the second surface R6 of the third positive lens 3 is -12.5 to -14 mm, and the semi-clear aperture is 11 to 14 mm. The first surface R7 of the fourth positive lens 4 has a curvature radius of 14.5 to 16 mm, and a semi-clear aperture of 11 to 14 mm; the second surface R8 of the fourth positive lens 4 has a curvature radius of -500 to 500 mm, and a semi-clear aperture of 11 to 14 mm.
[0021] More parameters of each lens are shown in Table 1.
[0022] Table 1 Lens parameters
[0023]
[0024] The design parameters of the large aperture optical system are as follows:
[0025] The focal length is 25mm, with an FNO of 1.5 to 1.7, a diffuse spot diameter of less than 5.5μm, and it is compatible with imaging chips up to 1 / 1.8. The relative transmittance is greater than 91%, and image quality is uniform. The lens accommodates a wide spectral range, from 400nm to 1100nm, providing excellent imaging both day and night. The effective aperture range is F1.5 to F1.7, providing clear imaging from an object distance of 0.5m to infinity, and excellent imaging in low-light environments.
[0026] The present invention is not limited to the above-mentioned optional implementation methods. Anyone can derive various other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that falls within the scope defined by the claims of the present invention shall fall within the scope of protection of the present invention.
Claims
1. A large aperture optical system, characterized by: The invention comprises a first positive lens (1), a second negative lens (2), a third positive lens (3) and a fourth positive lens (4) which are arranged in sequence from the object side to the image side; the refractive index ND of the first positive lens (1) is 1.56 to 1.66, and the Abbe number VD is 58 to 65; the refractive index ND of the second negative lens (2) is 1.7 to 1.83, and the Abbe number VD is 23 to 33; the refractive index ND of the third positive lens (3) is 1.56 to 1.66, and the Abbe number VD is 58 to 65; the refractive index ND of the fourth positive lens (4) is 1.56 to 1.66, and the Abbe number VD is 58 to 65.
2. The large aperture optical system according to claim 1, wherein: The curvature radius of the first surface of the first positive lens (1) is 16 to 19 mm, and the semi-clear aperture is 18 to 21 mm; the curvature radius of the second surface of the first positive lens (1) is -500 to 500 mm, and the semi-clear aperture is 18 to 21 mm.
3. The large aperture optical system according to claim 1, wherein: The curvature radius of the first surface of the second negative lens (2) is -15 to -13.5 mm, and the semi-clear aperture is 9 to 12 mm; the curvature radius of the second surface of the second negative lens (2) is 20 to 22 mm, and the semi-clear aperture is 9 to 12 mm.
4. The large aperture optical system according to claim 1, wherein: The curvature radius of the first surface of the third positive lens (3) is -500 to 500 mm, and the semi-clear aperture is 11 to 14 mm; the curvature radius of the second surface of the third positive lens (3) is -12.5 to -14 mm, and the semi-clear aperture is 11 to 14 mm.
5. The large aperture optical system according to claim 1, wherein: The curvature radius of the first surface of the fourth positive lens (4) is 14.5 to 16 mm, and the semi-clear aperture is 11 to 14 mm; the curvature radius of the second surface of the fourth positive lens (4) is -500 to 500 mm, and the semi-clear aperture is 11 to 14 mm.