Fabricating and Measuring Curved Customized Reflection Gratings for High Energy Spectroscopy

High energy grating spectrometers with high spectral resolution and effective area would make key contributions in studies of galaxy evolution and feedback, the winds of massive stars, and the energetics in the innermost regions around black holes. Gratings with fully-customizable attributes – period, substrate curvature, groove orientation, and blaze angle – are an enabling technology, unlocking new designs for spectrometers on missions ranging from SmallSats to flagships.

We report on the fabrication and characterization of customized gratings made using electron-beam lithography, a flexible, high resolution patterning technique. Large-format gratings on both flat and curved substrates have been fabricated, along with grating patterns that provide additional aberration-control in a diffractive optical system by using variable periods and curved grooves. These fabricated gratings are measured interferometrically to assess their limiting spectral resolution. Finally, we discuss future plans to manufacture a customized grating pattern on a thin, segmented X-ray optic and hence enable new reflection spectrometer designs for the soft X-ray.