Fabrication of a large-format blazed grating with radial grooves

Future soft x-ray spectrometers that use reflection grating technology typically call for arrays of custom gratings to be integrated into a Wolter-type telescope, where they intercept and disperse radiation coming to a focus over several meters. To enable both high spectral sensitivity and high spectral resolving power simultaneously, each grating requires blazed groove facets patterned over an aberration-correcting layout, such as a fanned, or “radial”, profile that matches the telescope focal length. A large-format master grating that meets such specifications with blazed, radial grooves has been fabricated at the Penn State Materials Research Institute and tested for spectral resolving power at the PANTER X-ray Test Facility of the Max Planck Institute. This presentation describes how the grating was fabricated using the electron-beam process of thermally-activated selective topography equilibration (TASTE), which has the key advantage of producing blazed groove facets in polymeric resist over a non-parallel groove layout not limited by substrate crystal structure.