Optical system with small zoom, large image plane and large aperture

Abstract

The invention provides an optical system with a small zoom, a large image plane and a large aperture, which can solve the technical problems of small image plane, low definition, small aperture, incomplete confocal infrared rays and the like. The optical system comprises a first lens group, a diaphragm, a second lens group, a third lens group, an optical filter and a photosensitive chip which aresequentially arranged from an object plane to an image plane; the focal length of the third lens group is a negative value, and the third lens group is fixed relative to the photosensitive chip; the focal length of the first lens group is a negative value, and the first lens group can move back and forth along the object image direction relative to the photosensitive chip; the focal length of thesecond lens group is a positive value, and the second lens group can move back and forth along the object image direction relative to the photosensitive chip; the second lens group comprises a fourthlens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens which are sequentially arranged along the object image direction; and the fourth lens and the ninth lens adopt glass aspheric lenses.

Description

【Technical Field】 [0001] The invention relates to the field of monitoring systems, in particular to an optical system with a small zoom, a large image surface and a large aperture. 【Background technique】 [0002] At present, the zoom optical system used for monitoring generally has such shortcomings, that is, the system has low definition, small aperture, and cannot guarantee the complete confocal of each focal length during the zooming process. At present, there are no lenses on the market that fully take the above characteristics into account. There are only a few lenses that improve certain aspects at the expense of other aspects. For example, in order to achieve ultra-high definition and infrared confocal, the aperture design is small, which cannot meet the requirements of surveillance lenses. The clarity requirements under low illumination conditions. [Content of the invention] [0003] The technical problem to be solved by the present invention is to provide a small zoom, l...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to provide an optical system with small zoom, large image surface and large aperture that can solve technical problems such as small image surface, low definition, small aperture, and infrared can not be completely confocal.

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