CN110412715A - Lens and its manufacturing method - Google Patents

Abstract

A lens comprises a first lens group with positive refractive power, an aperture, and a second lens group with positive refractive power arranged in sequence from a first side to a second side, wherein the total number of lenses with refractive power included in the lens is less than 4, and the lenses include at least 2 lenses with a refractive index greater than 1.7.

Description

Lens and its manufacturing method

technical field

The invention relates to a lens and a manufacturing method thereof.

Background technique

In recent years, with the advancement of technology, the types of lenses have become more and more diverse. Infrared lenses used in 3D sensors are a common lens. At present, the requirements for thinning and optical performance are getting higher and higher. To meet such requirements, the lens generally needs to have the characteristics of low cost, large aperture and light weight. Therefore, there is an urgent need for an imaging lens design that can take into account light weight, lower manufacturing cost and better imaging quality.

Contents of the invention

Other purposes and advantages of the present invention can be further understood from the technical features disclosed in the embodiments of the present invention.

According to an aspect of the present invention, a lens is provided, including a first lens group with positive diopter, an aperture, and a second lens group with positive diopter arranged in sequence from a first side to a second side. The total number of lenses with diopters is less than 4, and these lenses include at least 2 lenses with a refractive index greater than 1.7.

According to another aspect of the present invention, a lens includes a first lens with a negative diopter, a second lens with a positive diopter, an aperture, and a third lens with a positive diopter, which are sequentially arranged along the image enlargement side to the image reduction side, And the lens meets the following conditions: 0.2<L3D/LT<0.45, where L3D is the diameter of the lens surface of the third lens facing the image reduction side, LT is the lens surface of the first lens facing the image enlargement side to the third lens facing the image The distance of the lens surface on the reduction side, along the optical axis of the lens.

According to another aspect of the present invention, a lens includes a first lens group with a positive diopter, a diaphragm, and a second lens group with a positive diopter arranged in sequence along the image enlargement side to the image reduction side, wherein the first lens group consists of Composed of the first and second lenses with diopter, the second lens group is composed of the third lens with diopter, and the lens meets the following conditions: 2.5<EFL<3.0 and -2.0<L1f/EFL<-1.4, where EFL is the effective focal length of the lens, and L1f is the effective focal length of the first lens.

According to the above viewpoint of the present invention, it is possible to provide a lens design capable of light weight, lower manufacturing cost and better imaging quality.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited, and in conjunction with the accompanying drawings, the detailed description is as follows.

Description of drawings

FIG. 1 is a schematic diagram of a lens 10a according to an embodiment of the present invention.

2 to 4 are the ray fan diagram, field curvature diagram, distortion diagram, and relative illuminance diagram of the lens 10a, respectively.

FIG. 5 is a schematic diagram of a lens 10b according to an embodiment of the present invention.

6 to 8 are the ray fan diagram, field curvature diagram, distortion diagram, and relative illuminance diagram of the lens 10b, respectively.

Detailed ways

The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of the embodiments with reference to the drawings. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or back, etc., are only directions referring to the attached drawings. Accordingly, the directional terms are used to illustrate and not to limit the invention.

In addition, the terms "first" and "second" used in the following embodiments are used to identify the same or similar elements, and are not intended to limit the elements.

The so-called optical element in the present invention means that the element is made of partially or completely reflective or transmissive materials, usually consisting of glass or plastic. Examples are lenses, lenses, or apertures.

When the lens is used in the imaging system, the image enlargement side refers to the side on the optical path that is close to the object to be photographed, and the image reduction side refers to the side on the optical path that is closer to the photosensitive element.

The object side (or image side) of a lens has a convex surface (or concave surface) in a certain area, which means that the area is more "oriented" in the direction parallel to the optical axis than the radially outer area of the area. Outward convex" (or "inward concave").

FIG. 1 is a schematic diagram of the lens structure of the first embodiment of the present invention. Please refer to FIG. 1 , in this embodiment, the lens 10a has a lens barrel (not shown), and the lens barrel is arranged from the first side (image enlargement side OS) to the second side (image reduction side IS) to include the first Lens L1, second lens L2, aperture 14 and third lens L3. The first lens L1 and the second lens L2 can form a first lens group (for example, the front group) 20 with positive diopter, and the third lens L3 can form a second lens group (for example, the rear group) 30 with positive diopter. Furthermore, the image reduction side IS can be provided with a glass cover 16 and an image sensor (not shown in the figure), the imaging surface of the 850nm effective focal length of the lens 10a is marked as 18, and the glass cover 16 is located on the second lens group 30 and the effective focal length between the imaging surfaces 18 . In this embodiment, the diopters of the first lens L1 to the third lens L3 are negative, positive, and positive respectively, and the first lens and the third lens are aspherical glass lenses, but this embodiment of the present invention is not limited thereto . The image enlargement side OS of each specific embodiment of the present invention is set on the left side of each figure, and the image reduction side IS is set on the right side of each figure, and will not be described again.

The aperture 14 referred to in the present invention refers to an aperture stop, and the aperture is an independent component or integrated on other optical components. In this embodiment, the aperture uses mechanical components to block peripheral light while retaining light transmission in the middle to achieve a similar effect, and the aforementioned so-called mechanical components can be adjustable. The so-called adjustable refers to the adjustment of the position, shape or transparency of the mechanical components. Alternatively, the aperture can also be coated with an opaque light-absorbing material on the surface of the lens, and keep the central part of it transparent to achieve the effect of limiting the light path.

Each lens system defines a diameter of a surface. For example, as shown in FIG. 1 , the diameter of the surface refers to the distance between the inflection points P and Q of the mirror surface at both ends of the optical axis 12 in the direction perpendicular to the optical axis 12 (such as the diameter D1 of the surface). Furthermore, in this embodiment, the diameter of the surface S7 is 5.6 mm.

The design parameters of the lens and its peripheral elements of the lens 10a are shown in Table 1. However, the information listed below is not intended to limit the present invention. Anyone with ordinary knowledge in the field may make appropriate changes to its parameters or settings after referring to the present invention, but it still belongs to the scope of the present invention. within the category.

Table I

In Table 1, the pitch refers to the linear distance between two adjacent surfaces along the optical axis 12 of the lens 10a. For example, the pitch of the surface S1 is the linear distance between the surface S1 and the surface S2 along the optical axis 12 . The corresponding spacing, refractive index and Abbe number of each lens in the comment column should refer to the corresponding spacing, refractive index and Abbe number in the same column. In addition, in Table 1, the surface S1 and the surface S2 are two surfaces of the first lens L1. The surface S3 and the surface S4 are two surfaces of the second lens L2 . . . and so on. Surface S5 is aperture 14 . The surface S8 is the imaging surface 18 of the lens 10a.

The * appearing on the surface in the table means that the surface is an aspheric surface, and if it is not marked, it means a spherical surface.

In each of the following design examples of the present invention, the aspheric polynomial is represented by the following formula:

The above formula has been widely used. For example, Z is the offset in the direction of the optical axis (sag), c is the reciprocal of the radius of the osculating sphere, that is, the reciprocal of the radius of curvature near the optical axis 12, and k is the conic constant , r is the height of the aspheric surface, which is the height from the center of the lens to the edge of the lens. αi represent the aspheric coefficients of each order of the aspheric polynomial respectively. Table 2 lists the values of aspheric coefficients and conic coefficients of each order of the aspheric lens surface in the lens 10 a in this embodiment.

Table II

surface K a4 #6 α8 S1* -3.97 -9.92E-04 1.42E-05 -1.03E-07 S2* -0.99 -2.25E-05 -1.06E-04 1.97E-06 S6* -7.58 2.80E-03 -8.42E-05 2.41E-06 S7* 0 3.51E-03 6.95E-06 4.47E-06

The radius of curvature refers to the reciprocal of the curvature. When the radius of curvature is positive, the spherical center of the lens surface is in the direction of the image reduction side of the lens. When the radius of curvature is negative, the spherical center of the lens surface is in the direction of the image magnification side of the lens. The convex and concave of each lens can be seen in Table 1.

The aperture value of the present invention is represented by F/#, as indicated in Table 1. When the lens of the present invention is applied in a projection system, the imaging surface is the surface of the light valve. When the lens is used in the imaging system, the imaging surface refers to the surface of the photosensitive element.

In the present invention, the total lens length is represented by LT. More specifically, the total length of the lens in the present invention refers to the distance measured along the optical axis 12 between the optical surface S1 of the lens 10a closest to the image enlargement side and the optical surface S7 closest to the image reduction side, as indicated in Table 1 By.

In the present invention, the total lens imaging length is represented by TTL. More specifically, the total imaging length of the lens in the present invention refers to the distance measured along the optical axis 12 between the optical surface S1 of the lens 10a closest to the image magnification side and the imaging surface S8, as indicated in Table 1.

In this embodiment, the effective focal length of the first lens group (front group) is 108.48mm, the effective focal length of the second lens group (rear group) is 5.57mm, and the effective focal length of the first lens is -4.52mm, which is based on L1f express.

2 to 4 are diagrams of imaging optical simulation data of the lens 10a of this embodiment. 2 is a ray fan plot of infrared light, where the X-axis is the position where the light passes through the entrance pupil, and the Y-axis is the relative value of the position where the principal ray is projected onto the image plane (such as the imaging surface S8). Figure 3 is a field curvature diagram and a distortion diagram, where the horizontal axis of the field curvature diagram represents the distance from the focal plane, and the vertical axis represents the field from 0 to the maximum; the horizontal axis of the distortion diagram represents the percentage of distortion , the vertical axis represents the field from 0 to the maximum. Figure 4 shows the relative illuminance of lens 10a. From FIGS. 2 to 4 , it can be clearly seen that the lens 10 a in FIG. 1 has good imaging quality, and thus it can be verified that the lens 10 a of this embodiment can indeed have the characteristics of good optical imaging quality.

The lens of one embodiment of the present invention can include two lens groups. For example, the front group can use a lens with negative diopter (such as the first lens L1), and cooperate with a lens with positive diopter (such as the second lens L2) to improve light collection. capability, but it is not limited. The aperture value of the lens is less than or equal to 2.2. The rear group may include an aspheric lens (such as the third lens L3) to correct aberrations. The total number of lenses with a diopter in the lens is less than 4, and the lens includes at least 2 lenses with a refractive index greater than 1.7 or at least 2 lenses with an Abbe number less than 50.

In one embodiment, the lens may meet 2.5<EFL<3.0, in another embodiment may meet 2.6<EFL<2.9, and in yet another embodiment may meet 2.65<EFL<2.85, wherein EFL is the effective focal length of the lens. Furthermore, the lens can meet -2.0<L1f/EFL<-1.4, in another embodiment can meet -1.95<L1f/EFL<-1.5, and in yet another embodiment can meet -1.9<L1f/EFL<-1.6 , where L1f is the effective focal length of the first lens. In order to quickly converge the light entering the lens to achieve better optical effects in a limited space.

In one embodiment, the lens can meet 0.2<L3D/LT<0.45, in another embodiment can meet 0.23<L3D/LT<0.43, and in yet another embodiment can meet 0.26<L3D/LT<0.42, wherein L3D is the surface diameter of the third lens L3 facing the image reduction side IS (second side), LT is the surface S1 of the first lens of the lens facing the image enlargement side OS, and the surface S7 of the last lens facing the image reduction side IS is The length on the optical axis 12. In order to allow the light entering the lens to be imaged on the image sensor to obtain better optical effects in a limited space.

The design of the second embodiment of the lens of the present invention will be described below. FIG. 5 is a schematic diagram of the structure of the lens 10b according to the second embodiment of the present invention. In this embodiment, the diopters of the first lens L1 to the third lens L3 of the lens 10b are negative, positive, and positive respectively, all lenses are glass lenses, and the first lens L1 and the third lens L3 are aspheric lenses, In this embodiment, the aspheric lens can be made by glass molding. Furthermore, in this embodiment, the diameter of the surface S7 is 6.08 mm. The design parameters of the lens and its peripheral elements in the lens 10b are shown in Table 3.

Table three

Table 4 lists the values of aspheric coefficients and quadric surface coefficients of each order of the aspheric lens surface of the lens in the second embodiment of the present invention.

Table four

In this embodiment, the effective focal length of the first lens group (front group) is 24.83mm, the effective focal length of the second lens group (rear group) is 4.63mm, and the effective focal length of the first lens is -4.87mm, which is based on L1f express

6 to 8 are diagrams of imaging optical simulation data of the lens 10b of this embodiment. 6 is a ray fan plot of infrared light, wherein the X-axis is the position where the light passes through the entrance pupil, and the Y-axis is the relative value of the position where the principal ray is projected onto the image plane (such as the imaging surface S8). Figure 7 is a field curvature diagram and a distortion diagram, where the horizontal axis of the field curvature diagram represents the distance from the focal plane, and the vertical axis represents the field from 0 to the maximum; the horizontal axis of the distortion diagram represents the percentage of distortion , the vertical axis represents the field from 0 to the maximum. Figure 8 shows the relative illuminance of lens 10b. From FIGS. 6 to 8 , it can be clearly seen that the lens 10 b in FIG. 5 has good imaging quality, so it can be verified that the lens 10 b of this embodiment can indeed have the characteristics of good optical imaging quality. As can be seen from the above, the embodiments of the present invention can be applied to 3D sensors, and the wavelength used is 850nm. In a limited space, a sensor that can take into account light weight, lower manufacturing cost and better imaging quality can be provided. lens design.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, may use the method and technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes, but if they do not depart from the content of the technical solution of the present invention, Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims (10)

1. a kind of camera lens, characterized by comprising:

One first lens group and diopter being positive along one first side to the diopter that a second side is set in sequence be positive one Two lens groups；And

One aperture is set between first lens group and second lens group；

Wherein the camera lens includes to have the lens total number of diopter less than 4, and wherein those lens include that at least 2 refractive index are big In 1.7 lens.

2. a kind of camera lens, characterized by comprising:

One first lens group and diopter being positive along an image zoom side to the diopter that an image reduced side is set in sequence be One second positive lens group；And

One aperture is set between first lens group and second lens group；

Wherein first lens group is made of one first lens and one second lens of tool diopter, and second lens group is by having One the third lens of diopter are formed, and the camera lens meets following condition:

2.5 < EFL < 3.0 and -2.0 < L1f/EFL < -1.4, wherein EFL is the effective focal length of the camera lens, and L1f is first lens Effective focal length.

3. a kind of camera lens, characterized by comprising:

One first lens, the diopter being negative along an image zoom side to the diopter that an image reduced side is set in sequence are positive The third lens that one second spherical lens, an aperture and diopter are positive；And

The camera lens meets following condition:

0.2 < L3D/LT < 0.45, wherein L3D is the lens surface diameter that the third lens face the image reduced side, and LT is should First lens face faces the lens surface of the image reduced side to the lens surface of the image zoom side to the third lens, and edge should One distance of one optical axis of camera lens.

4. the camera lens as described in any one of claims 1 to 3, which is characterized in that the camera lens includes at least 2 Abbe numbers less than 50 Lens.

5. the camera lens as described in any one of claims 1 to 3, which is characterized in that the camera lens meets one of following condition: (1) In Include a piece of non-spherical lens between first side or the image zoom side and the aperture, (2) in the aperture and the second side or It only include a piece of non-spherical lens between the image reduced side, the material of (3) all lens is made of glass.

6. the camera lens as described in any one of claims 1 to 3, which is characterized in that the f-number of the camera lens is less than or equal to 2.2.

7. the camera lens as described in any one of claims 1 to 3, which is characterized in that the camera lens overall length of the camera lens is less than 20.

8. the camera lens as described in any one of claims 1 to 3, which is characterized in that the lens imaging overall length of the camera lens is between 20 Hes Between 40.

9. the camera lens as described in any one of claims 1 to 3, which is characterized in that the camera lens meets one of following condition: (1) certainly First side or the image zoom side to second side or the image reduced side are sequentially meniscus, biconvex lens and lenticular Mirror, (2) are sequentially that non-spherical lens, spherical surface are saturating from first side or the image zoom side to second side or the image reduced side Mirror and non-spherical lens.

10. a kind of camera lens manufacturing method, characterized by comprising:

One lens barrel is provided；

One first lens group that diopter is positive and one second lens group that diopter is positive are placed in and are fixed in the lens barrel, Wherein lens total number of the camera lens comprising diopter is less than 4, and those lens include that at least 2 refractive index are saturating greater than 1.7 Mirror.