Multi-focus objective lens

Abstract

The invention relates to a multi-focus object lens, which comprises a first surface and a second surface, wherein, the first surface comprises a first aspheric surface, a second aspheric surface, a first diffraction structure and a second diffraction structure; the first aspheric surface and the first diffraction structure are positioned in a first region; the second aspheric surface and the second diffraction structure are positioned in a second region which encloses the first region; the second surface comprises a third aspheric surface, a fourth aspheric surface, a third diffraction structure and a fourth diffraction structure; the third aspheric surface and the third diffraction structure are positioned in a third region; the fourth aspheric surface and the fourth diffraction structure are positioned in a fourth region which encloses the third region; the second surface is the reverse side of the first surface.

Description

technical field [0001] The invention relates to a multi-focus objective lens, in particular to an easier-to-manufacture multi-focus objective lens. Background technique [0002] The traditional multi-focus objective lens, as disclosed in US Patent Publication No. 2006 / 0201250, is an objective lens composed of two lenses, the weight of the objective lens is relatively heavy, and the cost of assembly and adjustment is relatively high. Moreover, since the lens needs to be manufactured using a semiconductor process, the cost is relatively high, and the problem of stray light is likely to occur. [0003] U.S. Patent Publication No. 2005 / 0281172 discloses a multi-focus objective lens with a single lens. The multi-focus objective lens has a diffractive structure, a first surface, and a second surface. The first surface is opposite to the second surface. The diffraction structure is formed on the first surface. The diffraction fringe spacing of the diffraction structure of US Pate...

AI Technical Summary

Problems solved by technology

The diffraction fringe spacing of the diffraction structure of US Patent Publication No. 2005 / 0281172 needs to be less than 3 μm, and the depth of the diffraction fringes is about 2.24 μm. The diffraction structure needs to be produced by high-precision processing, and its manufacturing cost and difficulty are high

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