Alignment tolerances for off-plane reflection grating spectroscopy: theoretical calculations and laboratory techniques

Off-plane reflection gratings can be used to provide high throughput and spectral resolution in the 0.3-2.0 keV band, allowing for unprecedented diagnostics of energetic astrophysical processes. A grating spectrometer consists of multiple aligned gratings intersecting the converging beam of a Wolter-I telescope. Each grating will be aligned such that the diffracted spectra overlap at the focal plane. Misalignments will degrade both spectral resolution and effective area. In this paper we present a summary of analytical alignment tolerance calculations, including an investigation of diffraction efficiency alignment dependence. Our plan for extending this work to future modeling and simulation is laid out. Finally, we report on the status of laboratory techniques to achieve these tolerances for flight-like optics.