Fabrication of Ultraviolet Transmission Blazed Grating for Slitless Spectrometer

Abstract

Slitless spectral sky surveys have been the focus of international astronomical research nowadays. Space-based surveys can obtain more spectral information in the ultraviolet and near-infrared bands than ground-based surveys. Dispersive elements constrain the development of space-based surveys, so we have conducted a series of studies on UV transmission blazed gratings. Through holographic interference lithography, the pattern is generated, then the pattern is transferred to the substrate by vertical ion beam etching to form a grating mask. Using the grating mask to block the tilted ion beam, different parts of the bottom of the grooves are bombarded by the ion beam with different fluxes, thus obtaining an asymmetric groove. The main composition of the deposition in the tilted ion beam etching and their effects on the groove shape and blazing angle were analyzed. The UV transmission blazed grating with a linear density of 333 lines/mm, and blazing angles of 13.2∘ and 10.5∘ were successfully fabricated with a peak diffraction efficiency of 88% and 92% of the theoretical value, respectively, which laid the foundation for the fabrication of high diffraction efficiency UV transmission blazed gratings.