Blazed reflection gratings with electron-beam lithography and ion-beam etching

Abstract

In modern X-ray-grating development for astronomical applications, electron-beam lithography has emerged as a primary fabrication approach to producing high-performance reflection gratings for both current and future missions. The work presented here leverages years of development in electron-beam lithography for X-ray gratings to produce a grating pattern that is then blazed with ion-beam etching. The directional ion-beam etching reshapes the groove facets to a consistent, triangular profile with a facet angle specified by the grating application. An initial prototype X-ray reflection grating fabricated with a combination of electron-beam lithography and ion-beam etching is presented here, along with diffraction efficiency performance measured across the soft-X-ray bandpass. This first prototype achieves ≈33% absolute diffraction efficiency from 0.2 to 1.2 keV, with an average peak-order efficiency of ≈17%. The fabrication approach, efficiency measurements, and path toward improved performance are presented.