Axial line focusing spiral zone plate

Abstract

The invention discloses an axial line focusing spiral zone plate. The zone plate is formed by alternately arranging a series of discontinuous spiral light transmitting ring bands and light shielding ring bands. The coordinates of the spiral ring bands in different cycles are adjusted in a certain distributing mode, so that incident light passes through the ring bands in the different cycles to be focused at different focal points, and a hollow-column-shaped line focal point is formed. Compared with a common spiral zone plate with same numerical apertures, the size of the focal point on an optical axis is effectively lengthened; designing and manufacturing are convenient and rapid, and only a production formula of the spiral ring bands and focal distances corresponding to the cycles need to be designed according to requirements; practical application and practical popularization are easy, and particularly practical application to and practical popularization for the vacuum-ultraviolet-ray waveband to the soft-X-ray waveband are easy; the axial line focusing spiral zone plate has broad application prospects in the researching fields such as particulate control, extreme ultra-violet lithography, astronomy, microscopes and micro power systems.

Description

technical field [0001] The invention belongs to the field of diffractive optics, in particular to an axial line focusing helical zone plate. Background technique [0002] As an important branch of modern optics, singularity optics has developed rapidly in recent years. At the phase singularity, the phase of the optical wave field becomes indeterminate, and the amplitude of the field is zero. The optical vortex is a special light field, which has the characteristics of spiral wavefront and orbital angular momentum. There is a phase singularity in the center of the beam, and it has a dark hollow structure. It has become a hot research topic in the academic circle in recent years. Scholars at home and abroad have proposed methods such as geometric mode conversion, hologram, spiral phase plate / zone plate, liquid crystal spatial light modulation, etc. It shows attractive application prospects. In particular, in the field of X-rays, considering that the vortex beam as an optica...

AI Technical Summary

Problems solved by technology

However, for conventional focusing systems, there is a contradictory relationship between axial line focus and small focus spot, that is, a small focus spot requires a larger numerical aperture, while a focus with a large axial size requires a smaller numerical aperture

However, there is no relevant report on the generation of axial line focusing vortex light field

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