SPIRAL ZONE PLATE Russian patent published in 2025 - IPC G02B5/18 

FIELD: physics.

SUBSTANCE: invention relates to an optical device comprising a spiral zone plate, wherein the optical device acts as a special optical element and can be used where generation of laser beams with non-zero orbital angular momentum is required, for example, to create systems for optical data transmission through free space (atmosphere), capturing particles, micro processing, obtaining images in thick media, etc. In the spiral plate, made in the form of a diffraction optical element, the phase profile of which is formed by isophase lines, made in the form of a single- or multi-turn spiral, the novelty is that the boundaries of the opaque m-th spiral are located in accordance with the condition: where r, θ are polar coordinates; M is number of multi-turn spiral; F is focal distance of spiral zone plate, λ is the radiation wavelength and r₀ is the radius of the central opaque zone of an arbitrary value not exceeding the radius of the first Fresnel zone of the equivalent classical Fresnel zone plate.

EFFECT: development of a plate with an additional parameter, which provides focusing of radiation into an annular region, which converts an incident plane wave into a vortex wave and which enables optimization of its characteristics.

1 cl, 3 dwg