We have fabricated the four flight gratings for a sounding rocket high-resolution spectrometer using a holographic ion-etching technique. The gratings are spherical (4000-mm radius of curvature), large (160 mm × 90 mm), and have a laminar groove profile of high density (3600 grooves/mm). They have been coated with a high-reflectance multilayer of Mo/Si. Using an atomic force microscope, we examined the surface characteristics of the first grating before and after multilayer coating. The average roughness is approximately 3 Å rms after coating. Using synchrotron radiation, we completed an efficiency calibration map over the wavelength range 225–245 Å. At an angle of incidence of 5° and a wavelength of 234 Å, the average efficiency in the first inside order is 10.4 ± 0.5%, and the derived groove efficiency is 34.8 ± 1.6%. These values exceed all previously published results for a high-density grating.
© 1999 Optical Society of AmericaPDF Article