Ultra-thin varifocal optical system with low cost, simple process and very low temperature drift

Abstract

The invention discloses an ultra-thin varifocal optical system with low cost, simple process and very low temperature drift, which comprises a photosensitive chip, a first lens group, a second lens group and a third lens group, wherein the distance between the first lens group and the second lens group gradually increases during the change from short focus to long focus; the distance between the second lens group and the third lens group gradually decreases during the change from short focus to long focus; one eyeglass of the third lens group adopts a non-spherical lens which can greatly improve the resolving capability level and shorten the thickness of the third lens group, a diaphragm is arranged between the second lens group and the third lens group, and a fourth lens group is arranged behind the third lens group. The invention has the characteristics of low cost, ultra-thin structure, simple process, very low temperature shift, and the like, and can reach 28mm wide angle and below 7 times zoom ratio.

Description

【Technical field】 [0001] The invention relates to a zoom optical system, in particular to a low-cost, ultra-thin, simple process, extremely low temperature drift, wide-angle zoom of 28mm (135mm focal length) and a zoom ratio of less than 7 times applied to a camera system. optical system. 【Background technique】 [0002] At present, the mainstream ultra-thin digital camera wide-angle lens with a zoom ratio of 4.5 to 7 times mainly adopts more than 10 lenses, and all of them need to use multiple glass aspheric surfaces to realize. However, glass aspheric technology is mainly in the hands of Japanese companies and is expensive. For glass aspheric lenses with the same volume and shape, the unit price without molds is 4 to 8 times that of glass spherical lenses, and more than 30 times that of plastic aspheric lenses; the mold cost is more than 150 times that of glass spherical lens molds. More than 15 times that of plastic aspheric lens molds. [0003] The supply of glass asph...

AI Technical Summary

Problems solved by technology

When the focal length of the lens changes greatly, there will be two situations in the 4.5-7x zoom lens: 1. The back focus distance drifts beyond the focus range, so that the lens cannot image normally; 2. The moving range of the focus group needs to be enlarged , which increases focusing time and reduces performance

[0005] Among the wide-angle lenses of ultra-thin digital cameras with a zoom ratio of 4.5 to 7 times that have been released so far, the design schemes that use less than 10 lenses and no more than 2 aspheric lenses have not reached the focal length of 28mm (135 focal lengths) at the wide-angle end. wide angle, all greater than 28mm

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