Development and fabrication of an EUV, ultra-low blaze angle diffraction grating for a NASA space telescope

The NASA Extreme Ultraviolet Explorer (EUVE) launched in 1992 was the first and last dedicated space telescope to operate in the EUV band. Although difficult to access due to the large interstellar extinction, the EUV range is important to understand the physical processes happening in million degree plasmas such as in hot white dwarf atmospheres, accretion processes, the interstellar medium and others. In addition, EUV radiation drives the atmospheric escape of all planets and is therefore critical to measure in order to understand the impact of host stars on the habitability potential of their exoplanets. Since the 1990s, technological advances have been made and are now enabling a renaissance for EUV missions, thanks in part to the possibilities offered by nanofabrication techniques to create high-efficiency diffraction gratings tailored to that wavelength range. We will summarize the recent advances made in the fabrication of ultra-low blaze angle diffraction gratings in the context of the NASA CubeSat MANTIS (Monitoring Activity of Nearby stars with ultraviolet Imaging and Spectroscopy), and will present preliminary test results on realized prototypes.