A transforming lens for generating Bessel beams

Abstract

A transforming lens generating Bessel wave beams comprises two outer layer dielectric lenses and a core layer dielectric lens. The outer layer dielectric lenses are low dielectric constant dielectric sheets, and phase shift units with 0-90 degree insertion phase shift are distributed on the outer layer dielectric lenses according to a square grid. The core layer dielectric lens is a high dielectric constant dielectric sheet, and phase shift units with 0 / 180 degree insertion phase shift are distributed on the core layer dielectric lens according to a square grid. The dielectric transforming lens can transform incident Gaussian wave beams into the Bessel wave beams, and has the advantages of being high in transformation efficiency, diverse in wave beam transformation, easy to machine and install and the like.

Description

technical field [0001] The invention relates to a lens, in particular to a transformation lens for generating Bessel beams. Background technique [0002] The Bessel beam has the characteristics of beamforming and can propagate a considerable distance in a non-diffraction manner, and has been deeply studied in the field of optics. With the development of microwave and millimeter wave technology, it is necessary to generate Bessel beams capable of beamforming transmission in the microwave and millimeter wave frequency band. [0003] In the field of optics, Bessel beams can be generated by transformations such as the annular slit method and holographic imaging, but these methods are difficult to implement in the microwave and millimeter wave bands, and the conversion efficiency is low. In the field of microwave and millimeter wave, a relatively simple conversion lens is an axicon lens, which can transform an incident Gaussian beam into a zero-order Bessel beam, but the middle ...

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Problems solved by technology

[0003] In the field of optics, Bessel beams can be generated by transformations such as the annular slit method and holographic imaging, but these methods are difficult to implement in the microwave and millimeter wave bands, and the conversion efficiency is low

In the field of microwave and millimeter wave, a relatively simple conversion lens is an axicon lens, which can transform an incident Gaussian beam into a zero-order Bessel beam, but the middle part of the medium layer of the axicon lens is thick and the edge part is thin. There is loss when passing through the dielectric layer. The medium in the middle part of the axicon lens is thick and the loss is large. Therefore, the conversion efficiency of the axicon lens to electromagnetic beams is low. Generate zero-order Bessel beams, and cannot generate other-order Bessel beams

Another transformation lens is a binary diffractive lens, which controls the phase on the lens aperture surface by controlling the thickness of the medium at different positions on the lens, and can efficiently transform Gaussian beams into Bessel beams in the millimeter wave and submillimeter wave frequency bands. However, the binary diffractive lens controls the phase on the lens aperture surface through the thickness of the medium at different positions on the medium lens. In the position where the phase of the lens aperture surface changes sharply, there will be sudden thickening and sudden thinning of the medium. During processing, the suddenly thickened protrusion is easy to break, and the suddenly thinned deep groove processing tool is difficult to reach, so the processing is difficult. At the same time, the thickness of the medium at each position of the binary diffractive lens is different, and the lens is not a planar structure, which makes it difficult to lay the lens flat. , it is difficult to install and save

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