Projection optical system

Abstract

The invention discloses a projection optical system, wherein a first lens group is used for focusing, a second lens group, a third lens group and a fourth lens group are used for zooming, and a diaphragm is located between the third lens group and the fourth lens group. At least one surface of a first lens of the first lens group is an aspheric surface. The field angle of the optical system can be improved, and off-axis aberration and distortion can be well corrected. At least one surface of a fifth lens in the fourth lens group is an aspheric surface, and an aspheric lens is configured behind a diaphragm, so that the aberration of the optical system can be well corrected, and the MTF performance is improved. The projection optical system can meet the requirements of large aperture, simple and miniaturized structure and low cost by optimally designing the number of the lenses of each lens group, the surface shape of each lens and various optical parameters of the lenses, and can effectively improve the aberration of the system and suppress the distortion of the system.

Description

technical field [0001] The invention relates to the technical field of optical lenses, in particular to a projection optical system. Background technique [0002] With the demand of the market, the zoom lens can obtain images of different sizes through continuous zoom without changing the working distance, and the zoom lens will be more and more used. There are more and more demands for projection in different places, such as home theater, classroom teaching, conference room and so on. Affected by external ambient light in actual scene applications, not only high requirements are placed on imaging quality, but also higher and higher requirements on the brightness of projection images. [0003] In order to meet the needs of the current situation, for the optical system used for projection, it tends to design a lens with a larger diameter to effectively obtain more light, which can make the projection screen obtain higher brightness. At present, the Fno design value of the p...

AI Technical Summary

Problems solved by technology

At present, the Fno design value of the projection lens is F1.7, and there are the following difficulties in designing a larger-diameter lens: the correction of system off-axis aberration and distortion correction, and the design of a high-performance MTF zoom lens usually has a large structure and is relatively difficult to use. More lenses, so the structure of the lens becomes more complicated and the cost is higher

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