Dynamic phase control by rigid spiralized Fresnel zone plates

Compact Fresnel lensing has been extensively used to achieve efficient management of the optical front. The further ability of dynamic tunability generally requires geometric reshaping through elastic deformations. Spiralized lens devices are able to present this property thanks to their substructured elongated configuration; nevertheless, elasticity is still subject to unavoidable limitations due to the limited flexibility of adoptable materials; thus, a non-flexible variant of these structures is quite more convenient. Here we describe a way to promote dynamic continuous light transmission through synchronous displacements of rigid spirals. The general design theory is explained to show the versatility of this new technology. A special study is devoted to the promotion of a controllable phase delay device, based on the Fresnel zone plate design, to promote perfectly endless and continuous linear phase transitions. (C) 2019 Optical Society of America.