Single-focus binary Fresnel zone plate

In this work, we propose and analyze a novel kind of binary Fresnel zone plate with single focus. It consists of a Fresnel zone plate whose zones have rough edges. We give analytical results for the intensity along the optical axis and demonstrate that lateral roughness of the zones produces the disappearance of secondary foci as a blurring of the edges. Besides, we corroborate its behavior by numerical simulations and experiments. This kind of Fresnel zone plate can be useful in a wide range of photonic applications, even for focusing with soft and hard X-rays or extreme ultraviolet radiation.