Assessing the Performance of Customized Gratings for X-ray Spectroscopy

High energy grating spectrometers with high spectral resolution and effective area would make key contributions in studies of galaxy evolution and feedback, how the winds of massive stars impact their surroundings, and physical attributes of winds launched from the innermost regions around black holes. Gratings with fully-customizable attributes – period, substrate curvature, groove orientation, and blaze angle – are an enabling technology for new spectrometer designs, facilitating both aberration-control for high resolution and substantial throughput. Such gratings are an essential technology for several proposed high-resolution spectroscopy instruments, but require further study.

We report on progress making such customized gratings using electron-beam lithography, a technique which rasters an accelerated beam of electrons to pattern photoresist. We summarize recent measurements assessing the limiting spectral resolution of flat, EBL-patterned gratings using interferometric techniques, and discuss the path forward for making and measuring the performance of curved gratings with aberration-correcting patterns.