Efficiency calibration of the first multilayer-coated holographic ion-etched flight grating for a sounding rocket high-resolution spectrometer

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 x 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 Angstrom rms after coating. Using synchrotron radiation, we completed an efficiency calibration map over the wavelength range 225-245 Angstrom. At an angle of incidence of 5 degrees and a wavelength of 234 Angstrom, 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. (C) 1999 Optical Society of America. OCIS codes: 050.1950, 120.6200, 120.6660, 260.7200, 310.1620, 350.1260.