Normalized frequency spectrum compression-based long focal length focusing lens and design method

Abstract

A normalized frequency spectrum compression-based long focal length focusing lens is disclosed and is used for realizing ultra long focal length focusing focal spots via compression of Fourier frequency spectrum of a focusing device relative to spatial cut off frequency. The lens has an annular metal-medium structure, auxiliary design wavelength and auxiliary design focal length are calculated, amplitude distribution and phase distribution of the lens are optimized, ultra diffraction focusing of ultra long focal length is realized, and transverse dimensions of the focal spots are enabled to besmaller than diffraction limits in a scope in which focal depth is greater than 100 time wavelength. Via use of the lens disclosed in the invention, design complexity and a calculation quantity of ultra long focal length long focal length and ultra diffraction lenses can be greatly reduced, and difficult problems that ultra long focal length and ultra diffraction focal spots are hard to realizedvia a conventional lens design method can be solved. The focusing lens is great in application prospects in the fields of particle control, super-resolution optical microscopy, high density data storage and the like. Besides an optical wave band, the use of the lens can also be expanded to other wave bands of electromagnetic waves; the lens disclosed in the invention can be widely applied to design and realization of electromagnetic wave function devices.

Description

technical field [0001] The invention belongs to the fields of light focusing, light imaging and light field regulation, and in particular relates to an ultra-telephoto deep super-diffraction focusing lens. Background technique [0002] For conventional super-diffraction lenses, it is usually difficult to achieve a super-diffraction solid focal spot or a super-diffraction hollow focal spot with a focal depth of 100λ. , particle manipulation, high-density data storage, super-resolution lithography and other aspects have important application value. At the same time, the traditional telephoto deep superdiffraction solid focal spot or superdiffractive hollow focal spot lens design requires a huge amount of calculation, which usually takes N points (N is an integer), and optimize the design of each point, the amount of calculation increases linearly with the increase of the focal depth (equivalent to the optimal design of N lenses), it is difficult to optimize the design accordi...

AI Technical Summary

Problems solved by technology

At the same time, the traditional telephoto deep superdiffraction solid focal spot or superdiffractive hollow focal spot lens design requires a huge amount of calculation, which usually takes N points (N is an integer), and optimize the design of each point, the amount of calculation increases linearly with the increase of the focal depth (equivalent to the optimal design of N lenses), it is difficult to optimize the design according to the target parameters (operating wavelength λ, lens radius R, lens focal length f , lens focal depth DOF, focal spot size FWHM), to achieve a super-diffraction lens design with a focal depth greater than 20λ (or super-diffractive hollow focal spot)

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