CN212965590U

CN212965590U - Short-focus infrared imaging lens

Info

Publication number: CN212965590U
Application number: CN202021748938.9U
Authority: CN
Inventors: 吴强华; 张福美; 汪晓旭
Original assignee: Jiangxi Telaisi Optical Co ltd
Current assignee: Jiangxi Telaisi Optical Co ltd
Priority date: 2020-08-20
Filing date: 2020-08-20
Publication date: 2021-04-13
Anticipated expiration: 2030-08-20

Abstract

The utility model discloses a short burnt infrared imaging lens includes from the object plane to image plane along the optical axis in proper order: a first lens having a negative focal length, a second lens having a positive focal length, a third lens having a negative focal length, a fourth lens having a positive focal length, a fifth lens having a positive focal length, and a sixth lens having a negative focal length; the utility model discloses a camera lens comprises six lens, and is with low costs, and camera lens total length TTL is 15mm, and marginal luminance is high, the MTF of full field of view is even, effectively improves the imaging effect of camera lens, has effectively reduced infrared microspur imaging lens's length and has the microspur function.

Description

Short-focus infrared imaging lens

Technical Field

The utility model relates to an optical lens technical field, especially a short burnt infrared imaging lens.

Background

The infrared macro imaging lens in the current market has the defects of long length, large volume, complex structure and overlarge object distance.

SUMMERY OF THE UTILITY MODEL

The utility model discloses a solve current infrared macro imaging lens and have that length is long, bulky, the structure is complicated and the object distance is too big problem, provide a short burnt infrared imaging lens.

In order to achieve the purpose, the utility model is implemented according to the following technical scheme:

the utility model provides a short burnt infrared imaging lens, includes from the object plane to image plane along the optical axis in proper order: a first lens having a negative focal length, a second lens having a positive focal length, a third lens having a negative focal length, a fourth lens having a positive focal length, a fifth lens having a positive focal length, and a sixth lens having a negative focal length; the object surface side of the first lens is a convex surface, and the image surface side of the first lens is a concave surface; the object surface side of the second lens is a convex surface, and the image surface side of the second lens is a convex surface; the object plane side of the third lens is a concave surface, and the image plane side of the third lens is a concave surface; the object surface side of the fourth lens is a concave surface, and the image surface side of the fourth lens is a convex surface; the object surface side of the fifth lens is a convex surface, and the image surface side of the fifth lens is a convex surface; the object plane side of the sixth lens is a concave surface, and the image plane side of the sixth lens is a convex surface; a diaphragm is arranged between the third lens and the fourth lens, and protective glass is arranged on the image surface side of the sixth lens;

the focal length of the first lens is f1, the focal length of the second lens is f2, the overall focal length of the short-focus infrared imaging lens is f, and the following conditions are met: -2.06< (f/f1) < -0.87, 1.23< f/f2< 2.31.

As an optimized scheme of the utility model, the object distance of short burnt infrared imaging lens satisfies following scope: 6mm-16 mm.

As a preferable aspect of the present invention, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, and the following conditions are satisfied: -2.13< f6/f5< -0.78.

As a preferred scheme of the utility model, the total length of short burnt infrared imaging camera lens is TTL, and satisfies following condition: and the ttl is more than or equal to 14mm and less than or equal to 17 mm.

As a preferable embodiment of the present invention, the second lens and the third lens are a group of cemented lenses.

As a preferable aspect of the present invention, the fifth lens and the sixth lens are a group of cemented lenses.

Compared with the prior art, the utility model discloses a camera lens comprises six lens, and is with low costs, and camera lens total length TTL is 15mm, and marginal luminance is high, the MTF of full field of view is even, effectively improves the imaging effect of camera lens, has effectively reduced infrared macro imaging lens's length and has the macro function.

Drawings

Fig. 1 is a schematic view of a lens according to an embodiment of the present invention.

Fig. 2 is a first analysis diagram according to an embodiment of the present invention.

Fig. 3 is a second analysis diagram according to an embodiment of the present invention.

Fig. 4 is a field curvature diagram according to an embodiment of the present invention.

Fig. 5 is a distortion diagram of the embodiment of the present invention.

Fig. 6 is a relative illuminance diagram according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and embodiments. The specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

As shown in fig. 1, a short-focus infrared imaging lens of this embodiment sequentially includes, from an object plane to an image plane along an optical axis: a first lens E1 having a negative focal length, a second lens E2 having a positive focal length, a third lens E3 having a negative focal length, a fourth lens E4 having a positive focal length, a fifth lens E5 having a positive focal length, and a sixth lens E6 having a negative focal length; the object surface side of the first lens E1 is a convex surface, and the image surface side is a concave surface; the object surface side of the second lens E2 is a convex surface, and the image surface side is a convex surface; the object surface side of the third lens E3 is a concave surface, and the image surface side is a concave surface; the object surface side of the fourth lens E4 is a concave surface, and the image surface side is a convex surface; the object plane side of the fifth lens E5 is a convex surface, and the image plane side is a convex surface; the object plane side of the sixth lens E6 is a concave surface, and the image plane side is a convex surface; a diaphragm is arranged between the third lens E3 and the fourth lens E4, and protective glass E7 is arranged on the image surface side of the sixth lens E6;

the focal length of the first lens E1 is f1, the focal length of the second lens E2 is f2, the overall focal length of the short-focus infrared imaging lens is f, and the following conditions are met: -2.06< (f/f1) < -0.87, 1.23< f/f2< 2.31.

Further, the object distance of the short-focus infrared imaging lens meets the following range: 6mm-16 mm.

Further, the focal length of the fifth lens E5 is f5, the focal length of the sixth lens E6 is f6, and the following conditions are satisfied: -2.13< f6/f5< -0.78.

Further, the total length of the short-focus infrared imaging lens is TTL, and the following conditions are satisfied: and the ttl is more than or equal to 14mm and less than or equal to 17 mm.

Further, the second lens E2 and the third lens E3 are a group of cemented lenses.

Further, the fifth lens E5 and the sixth lens E6 are a group of cemented lenses.

Wherein: as shown in fig. 1, the object-side surface of the first lens E1 is S1, the image-side surface is S2, the object-side surface of the second lens E2 is S3, the cemented surface of the second lens E2 and the third lens E3 is S4, the image-side surface of the third lens E3 is S5, the object-side surface of the fourth lens E4 is S6, the image-side surface is S7, the object-side surface of the fifth lens E5 is S8, the cemented surface of the fifth lens E5 and the sixth lens E6 is S9, and the image-side surface of the sixth lens E6 is S10.

To verify the optical performance of the short-focus infrared imaging lens of the present embodiment, when the working distance is infinity, the total focal length f of the lens is 3.7mm, the FNO is 2.8, the field angle FOV is 64 °, the object distance is 10mm, and the parameters of the lens groups are listed in table 1 in sequence.

TABLE 1

In table 1: surf is the surface number, Radius is the Radius of curvature, Thickness is the lens Thickness, Index is the refractive Index, ABB is the Abbe number, EFL-E is the focal length.

From table 1, the parameters of each lens of the present embodiment satisfy the above design: -2.06< (f/f1) < -0.87, 1.23< f/f2<2.31, -2.13< f6/f5< -0.78.

As shown in fig. 2 and fig. 3, fig. 2 and fig. 3 are Modulation Transfer Function (MTF) value graphs of the present embodiment, which are based on the parameters in table 1, and the MTF value graph is defined to be greater than 0 and less than 1 based on the measurement of the quality such as the most important resolution of the optical lens, and the MTF value is closer to 1 in the field of the technology, which indicates that the performance of the lens is more excellent, i.e. the resolution is higher; the variable is the spatial frequency, namely how many lines can be presented in a range of one mm to measure the spatial frequency, and the unit is expressed by lp/mm; a fixed high frequency (e.g., 300lp/mm) curve represents the lens resolution characteristic, and the higher this curve, the higher the lens resolution, and the ordinate is the MTF value. The distance from the center of the image field to the measuring point can be set on the abscissa, the lens is of a symmetrical structure taking the optical axis as the center, the change rule of the imaging quality from the center to each direction is the same, and due to the influence of factors such as aberration and the like, the farther the distance between a certain point in the image field and the center of the image field is, the MTF value generally has a descending trend. Therefore, the distance from the center of the image field to the edge of the image field is taken as the abscissa, and the imaging quality of the edge of the lens can be reflected; in addition, at a position deviated from the center of the image field, MTF values measured by the sinusoidal gratings of the line in the tangential direction and the line in the radial direction are different; the MTF curve produced by a line parallel to the diameter is called the sagittal curve, denoted s (sagittal), and the MTF curve produced by a line parallel to the tangent is called the meridional curve, denoted t (meridian); in this way, there are generally two MTF curves, i.e. S curve and T curve, and in fig. 2 and 3, there are multiple sets of MTF variation curves using the distance from the center of the image field to the edge of the image field as the abscissa, which reflects that the lens system has a higher resolution and a resolution of 200 ten thousand pixels.

Fig. 2-6 sequentially show a first analytical diagram, a second analytical diagram, a field curvature diagram, a distortion diagram, and a relative illumination diagram of the compact wide-angle lens of the present embodiment when the working distance is infinity.

As shown in FIG. 4, the closer the curve is to the y-axis, the smaller the distortion rate, the control of the meridian curvature value within-0.06 and the control of the sagittal curvature value within-0.02-0.06. As shown in fig. 5, in which the optical distortion rate is controlled within the range of-11%. As shown in fig. 6, the relative illuminance is greater than 92%.

The technical scheme of the utility model is not limited to the restriction of above-mentioned specific embodiment, all according to the utility model discloses a technical scheme makes technical deformation, all falls into within the protection scope of the utility model.

Claims

1. The utility model provides a short burnt infrared imaging lens which characterized in that includes in proper order from the object plane to image plane along the optical axis: a first lens having a negative focal length, a second lens having a positive focal length, a third lens having a negative focal length, a fourth lens having a positive focal length, a fifth lens having a positive focal length, and a sixth lens having a negative focal length; the object surface side of the first lens is a convex surface, and the image surface side of the first lens is a concave surface; the object surface side of the second lens is a convex surface, and the image surface side of the second lens is a convex surface; the object plane side of the third lens is a concave surface, and the image plane side of the third lens is a concave surface; the object surface side of the fourth lens is a concave surface, and the image surface side of the fourth lens is a convex surface; the object surface side of the fifth lens is a convex surface, and the image surface side of the fifth lens is a convex surface; the object plane side of the sixth lens is a concave surface, and the image plane side of the sixth lens is a convex surface; a diaphragm is arranged between the third lens and the fourth lens, and protective glass is arranged on the image surface side of the sixth lens;

2. The short-focus infrared imaging lens of claim 1, characterized in that: the object distance of the short-focus infrared imaging lens meets the following range: 6mm-16 mm.

3. The short-focus infrared imaging lens of claim 1, characterized in that: the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, and the following conditions are met: -2.13< f6/f5< -0.78.

4. The short-focus infrared imaging lens of claim 1, characterized in that: the total length of the short-focus infrared imaging lens is TTL, and the following conditions are met: and the ttl is more than or equal to 14mm and less than or equal to 17 mm.

5. The short-focus infrared imaging lens of claim 1, characterized in that: the second lens and the third lens are a group of cemented lenses.

6. The short-focus infrared imaging lens of claim 1, characterized in that: the fifth lens and the sixth lens are a group of cemented lenses.