Focused ion beam fabrication procedures of x-ray micro fresnel zone plates

In this paper the use of focused ion beam (FIB) mask-less lithography is presented as a novel and simple way to fabricate x-ray Fresnel zone plates (FZPs), and a prototype of a FIB-made 100 nm resolution FZP with 38 zones is described. Considerations for future developments—the maximum aspect ratio achievable by FIB lithography in nickel, a way to produce zones with a parabolic transverse profile, as theoretically required for the highest efficiency in focusing—are also reported.