a zoom lens

Abstract

A zoom lens comprises, orderly from the object side to the image side, a first lens group G1 having the positive focal power, a second lens group G2 having the negative focal power, a third lens group G3 having the positive focal power, a fourth lens group G4 having the positive focal power, a fifth lens group G5 having the positive focal power. The first, third and fifth lens groups are fixed groups, the second negative lens group is a zoom group, and the fourth positive lens group is a focusing group. An aperture diaphragm STP having a specified and given caliber is configured between the second lens group G2 and the third lens group G3, a first light filter ICF and a second light filter LPF are configured between the fifth lens group G5 and an imaging surface IMG, and a light reception surface of a solid shooting element is configured on the imaging surface IMG. By moving a second lens, the zoom from a wide angle end to a telescopic end is realized, and by moving the fourth lens group along an optical axis, the correction and focusing of the image surface variation along with the zoom are carried out.

Description

technical field [0001] The invention relates to the technical fields of monitoring and security, in particular to a large-magnification, full-range infrared confocal zoom lens. Background technique [0002] Surveillance cameras are quasi-cameras used in security. They are mainly divided into gun-type, hemispherical, and high-speed dome-type in terms of appearance, and there are also distinctions between analog monitoring and IP network monitoring. Surveillance cameras are widely used in many security fields such as schools, companies, banks, transportation, and safe cities. In the past, although the pixels and resolution of surveillance cameras were higher than those of computer video heads, their pixels were still low compared with professional digital cameras or dvs. With the continuous development of imaging optical design technology, surveillance cameras have surpassed professional digital cameras and entered the era of megapixels. Most of the traditional surveillance ...

AI Technical Summary

Problems solved by technology

[0007] 2. Unable to be fully infrared confocal

Therefore, at the telephoto end, especially when the focal length reaches a long focal length of 200mm or more, it is extremely difficult to achieve infrared confocal, which will make it impossible for the surveillance camera to clearly monitor distant objects at night

[0010] 3. Short equivalent focal length and low zoom ratio

[0013] Traditional zoom lenses are limited by factors such as the sensor size and the actual focal length of the design, and often cannot achieve a large effective focal length, which makes it impossible for the lens to see distant objects clearly when monitoring

At the same time, most of the existing zoom lenses have a zoom ratio less than 20 times, which cannot meet the long-distance monitoring of several kilometers; and most surveillance cameras with a zoom ratio greater than 20 times cannot meet the needs of both day and night, and the image quality is poor. Inability to maintain high optical performance at all zoom positions

[0014] Although the zoom lens described in Patent Document 1 (103336355A) can meet the needs of both day and night, the zoom ratio is only about 3 times, so the imaging range is limited, and it cannot meet the long-distance monitoring of several kilometers.

[0015] Although the zoom lens described in Patent Document 2 (publication number 103293646A) has a zoom ratio of 30 times, the focal length at the telephoto end is only 129mm, so it cannot meet the needs of long-distance monitoring.

In addition, this patent cannot achieve infrared confocal, and cannot clearly image in the case of dark outdoor light, so it cannot meet the needs of both day and night.

Images