Fig. 9: Design methods of superoscillatory lenses.
From: Superoscillation: from physics to optical applications
a A particle swarm algorithm for SOL optimization; b the subdiffraction diffractionless beam optimization procedure; c the optimization-free design of a subdiffraction diffractionless beam. Equations (3) is given by f = z(0) and Zmax = z(R)−z(0), where z(r) = {1−[λ0/d(r)]2}1/2, d(r) = λ/sin(θ(r)), θ(r) = atan(r/f), R is the radius of the lens, Zmax is the beam propagation distance, λ0 and f0 are the working wavelength and focal length, and λ and f are the designing wavelength and focal length. Equation (1) is given by rn = [nλf + (nλ)2/4]1/2, where n is an integer. Reproduced with permission from ref. 130 Copyright 2018, The Optical Society of America
