3D Diffractive Lenses to Overcome the 3D Abby Diffraction Limit

Abstract

Radiation cannot be focused on anything smaller than its half of wavelength—or so says more than a century of physics wisdom. In the first part of this chapter the results of the focal fields of a phase correcting Fresnel lens examination are described for several small values of F/, with F ≦ 2λ which allows for overcoming Abbe barrier. It was also shown that the minimum diameter of the focal spot near the central circumferential step of binary diffractive axicon was equal to FWHM = 0.38λ. In the second part of this chapter the innovative radiating structures as a conical FZP lens are proposed for subwavelength focusing. It has been shown that in contrast to the flat diffractive optics the curvilinear 3D diffractive conical optics allows for overcoming 3D Abbe barrier with focal distance F more than F > 2λ.