Lightweight large target surface micro-light objective optical lens

Abstract

The application discloses a light-weighted large-target micro-light objective optical lens, which comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in sequence from an object side to an image side; the first lens is a plano-convex positive lens, the second lens is a convex-concave positive lens, the third lens is a double-concave negative lens, the fourth lens is a convex-concave cemented positive lens, and the fifth lens is a convex-concave positive lens. The light-weighted large-target micro-light objective optical lens has smaller volume, lighter weight, and is more convenient for focusing and realizing close-range observation, is convenient for portable holding, reduces the load of a focusing mechanism, and has a wider application range.

Description

Technical Field

[0001] This invention relates to an optical lens, and more particularly to a lightweight, large-area low-light objective lens, belonging to the field of optical system technology. Background Technology

[0002] With advancements in chip technology, the application of new photosensitive materials, and back-illumination techniques, high-sensitivity imaging chips have significantly improved image quality in night vision. Night vision products have found widespread application, including civilian uses such as day-and-night surveillance, night-vision vehicle driver assistance systems, and forest night vision cameras; and military uses such as day-and-night observation and aiming scopes, vehicle and airborne driver assistance systems, and border, river, and security monitoring. As night vision technology continues to develop and expand, the application of day-and-night optical lenses is also becoming increasingly widespread, representing a huge market potential.

[0003] Existing low-light objective optical systems reported mainly include Zhu Biao's helmet-mounted low-light night vision system, which has a short focal length of 6.7mm, can only be equipped with a 1 / 2 CMOS sensor, and has a very limited observation distance. Zhang Mingchao et al.'s low-light objective optical system has the aperture stop inside the lens, which results in a larger lens diameter and heavier weight for the same aperture conditions, making it unsuitable for handheld use. Furthermore, close-range focusing requires moving more than two lens elements, increasing the load on the focusing mechanism. Therefore, there is an urgent need for a lightweight, large-area low-light objective optical lens. Summary of the Invention

[0004] To address the shortcomings of the aforementioned technologies, this invention provides a lightweight, large-area low-light objective lens.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a lightweight large target surface low light objective lens, comprising a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially from the object side to the image side;

[0006] The first lens is a plano-convex positive lens, the second lens is a convex-concave positive lens, the third lens is a biconcave negative lens, the fourth lens is a convex-concave cemented positive lens, and the fifth lens is a convex-concave positive lens.

[0007] Preferably, the ratio of the focal length of the first lens to the focal length of the entire lens satisfies the following relationship:

[0008] 1.1 < |f1 / f| < 2;

[0009] Where f is the focal length of the entire lens, and f1 is the focal length of the first lens.

[0010] Preferably, the third lens is a high refractive index lens with a refractive index greater than 1.92.

[0011] Preferably, the fifth lens is a high refractive index lens with a refractive index greater than 1.92.

[0012] Preferably, the focal length of the entire lens is 55-90mm and the F-number is 1.2-1.4.

[0013] Preferably, the first lens is made of K9L optical glass, and its convex surface is provided with an aperture.

[0014] This invention provides a lightweight large-area low-light objective lens, which has a smaller size, lighter weight, and is easier to focus for close-up observation. It is also easy to hold, reduces the load on the focusing mechanism, and has a wider range of applications. Attached Figure Description

[0015] Figure 1 This is a structural diagram of the optical system according to an embodiment of the present invention.

[0016] Figure 2 This is an optical distortion diagram according to an embodiment of the present invention.

[0017] Figure 3 This is an MTF resolution curve diagram of an embodiment of the present invention.

[0018] In the diagram: 1. Aperture; 2. First lens; 3. Second lens; 4. Third lens; 5. Fourth lens; 6. Fifth lens. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] This embodiment provides a lightweight large-area low-light objective lens with a focal length f of 76mm and an F-number of 1.4. It comprises a first lens 2, a second lens 3, a third lens 4, a fourth lens 5, and a fifth lens 6 arranged sequentially from the object side to the image side. The specific structure is as follows: Figure 1 As shown.

[0021] Among them, the first lens 2 is a plano-convex positive lens, the second lens 3 is a convex-concave positive lens, the third lens 4 is a biconcave negative lens, the fourth lens 5 is a convex-concave cemented positive lens, and the fifth lens 6 is a convex-concave positive lens. The fifth lens 6 is used for focusing.

[0022] Preferably, the ratio of the focal length of the first lens 2 to the focal length of the entire lens satisfies the following relationship:

[0023] 1.1 < |f1 / f| < 2;

[0024] Where f is the focal length of the entire lens, and f1 is the focal length of the first lens. Preferably, f = 76mm and f1 = 101.9mm.

[0025] Preferably, the first lens 2 is made of K9L optical glass, and its convex surface is provided with an aperture 1.

[0026] The lightweight large-area low-light objective lens of this embodiment has a total of 5 lenses, including cemented lenses, making a total of eleven surfaces. The lenses are numbered sequentially from the first lens to the fifth lens, and their radii of curvature, lens center thickness, lens center distance, and lens refractive index satisfy the following conditions:

[0027]

[0028] like Figure 2 The diagram shown is an optical distortion diagram of this embodiment. Figure 2 It can be seen that its maximum distortion is only 3.6%. For example... Figure 3 The image shown is an MTF resolution curve of this embodiment, where the horizontal axis represents the spatial frequency of line pairs per millimeter, and the vertical axis represents the MTF value. Figure 3 As can be seen, this embodiment exhibits good contrast and high overall resolution within a spatial frequency range of 40 lp / mm.

[0029] In summary, the lightweight large-area low-light objective lens disclosed in this invention has the following beneficial effects:

[0030] First, the present invention places the aperture stop on the first surface, achieving the smallest size and lightest weight under the same focal length and F number conditions.

[0031] Secondly, the first lens of this invention is made of ordinary environmentally friendly K9L glass, which is lighter than other glass materials under the same size conditions, and is also cheaper.

[0032] Third, this invention fully utilizes the ease of processing glass lenses, using glass materials for all lenses, and the last lens is the smallest, serving as a focusing lens, making the entire system more compact and lightweight.

[0033] Fourth, the imaging target surface of the optical lens of this invention can reach 1 inch.

[0034] The above embodiments are not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solution of the present invention are also within the protection scope of the present invention.

Claims

1. A lightweight, large-area low-light objective lens, characterized in that: It consists of a first lens (2), a second lens (3), a third lens (4), a fourth lens (5), and a fifth lens (6) arranged sequentially from the object side to the image side; The first lens (2) is a plano-convex positive lens with its convex surface facing the object side; the second lens (3) is a convex-concave positive lens; the third lens (4) is a biconcave negative lens; the fourth lens (5) is a convex-concave cemented positive lens; the fourth lens is a cemented biconvex positive lens and a biconcave negative lens arranged sequentially from the object side to the image side; and the fifth lens (6) is a convex-concave positive lens. The ratio of the focal length of the first lens (2) to the focal length of the entire lens satisfies the following relationship: 1.1 < |f1 / f| < 2; Where f is the focal length of the entire lens, and f1 is the focal length of the first lens; The entire lens has a focal length of 55-90mm and an f-number of 1.2-1.

4.

2. The lightweight large-area low-light objective lens according to claim 1, characterized in that: The third lens (4) is a high refractive index lens with a refractive index greater than 1.

92.

3. The lightweight large-area low-light objective lens according to claim 2, characterized in that: The fifth lens (6) is a high refractive index lens with a refractive index greater than 1.

92.

4. The lightweight large-area low-light objective lens according to claim 3, characterized in that: The first lens (2) is made of K9L optical glass, and its convex surface is provided with an aperture (1).

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