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Lens

A lens and lens technology, applied in the field of lenses, can solve the problems of low picture value, less light transmission through the lens, and dark images, etc., and achieve the effects of reducing the total optical length, large target surface size, and good image quality

Active Publication Date: 2020-09-01
ZHEJIANG DAHUA TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Most of the lens structure is simple, and the size of the target surface is small, resulting in low resolution of the collected images, general shooting effect, and little picture value
Moreover, most of the zoom lenses currently on the market have small apertures, resulting in less light transmission through the lens, and darker images acquired in low-light scenes, making it difficult to guarantee image quality.

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0088] In the specific implementation process, the curvature radius R, central thickness Tc, refractive index Nd, and Abbe constant Vd of each lens of the lens meet the conditions listed in Table 1:

[0089]

[0090]

[0091] Table 1

[0092] The lens provided in Embodiment 1 has the following optical technical indicators:

[0093] Optical total length TTL≤115mm;

[0094] Lens focal length f': 55mm;

[0095] Field of view of the lens: 18.2°;

[0096] Optical distortion of the lens: -0.6%;

[0097] Aperture FNO. of the lens system: F1.3;

[0098] Lens image size: 1.1〞(≥Φ17.6mm).

[0099] The imaging system provided by this embodiment will be further introduced below through detailed analysis of the embodiment.

[0100] The optical transfer function is a more accurate, intuitive and common way to evaluate the imaging quality of an imaging system. The higher the curve and the smoother it is, the better the imaging quality of the system is. For various aberrations (suc...

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Abstract

The invention provides a lens. In the embodiment of the invention, four lens groups are sequentially arranged in the lens from an object side to an image side according to a specific sequence, and thelens groups in the lens satisfy the following conditions: 1.21 < = f1 / f '< = 1.41 and 2.25 < = TTL / ((BFL * f ') 1 / 2) < = 2.65; f1 is the focal length of the first lens group; f'is the focal length ofthe lens; TTL is the total optical length of the lens; and BFL is the distance between the fourth lens group and the image plane. The size of the target surface of the lens and the aperture are increased to a certain extent, so that the resolution of the acquired image is high, the light transmission amount of the lens can still be ensured in a low-illumination scene, the quality of the acquiredimage is good, and the total optical length of the lens is reduced. Therefore, the embodiment of the invention provides the lens which is small in size, large in target surface size and large in aperture.

Description

technical field [0001] The invention relates to the technical field of optical imaging, in particular to a lens. Background technique [0002] With the development of society, people's awareness of safety precautions has been continuously improved, and the security monitoring industry has also developed rapidly, and the role of monitoring is becoming more and more important. At present, monitoring fixed-focus lenses are widely used in people's daily life, but conventional security monitoring and road condition monitoring lenses have the following disadvantages: [0003] Most of the lens structure is simple, and the size of the target surface is small, resulting in low resolution of the collected images, general shooting effect, and little picture value. Moreover, most of the zoom lenses currently on the market have small apertures, resulting in less light transmission through the lens, and darker images acquired in low-light scenes, making it difficult to guarantee image qu...

Claims

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Application Information

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IPC IPC(8): G02B13/00
CPCG02B13/0015G02B13/0065
Inventor 刘凯杜艳芬丁洪兴
Owner ZHEJIANG DAHUA TECH