First-generation holographic, grazing-incidence gratings for use in converging, extreme-ultraviolet light beams

Abstract

We present two holographic recording solutions that produce gratings suitable for use at grazing incidence in the extreme ultraviolet. The rulings are formed when the interference pattern of two spherical wave fronts is recorded on a planar substrate. Each grating is designed to minimize or eliminate the dominant aberration terms in order to maximize the spectral and spatial resolution of the system. In the first design, the dominant astigmatism term in a power-series expansion of the light path function is eliminated; in the second design, the dominant comatic terms are minimized. Each grating is placed directly in a converging light beam at grazing incidence to provide high system efficiency in the extreme ultraviolet. The aberration control afforded by both recording solutions is excellent, providing detector-limited spatial and spectral resolution over much of the usable bandpass. Furthermore, the aberration control is maintained over a wide range of beam speeds and off-axis angles, thereby outperforming conventional varied line-space gratings for use in the extreme ultraviolet. We discuss the methodology used to develop the recording solutions, model and compare the performance of the gratings, and discuss possible space-based applications for these gratings.