EFFICIENCY OF A MULTILAYER-COATED, ION-ETCHED LAMINAR HOLOGRAPHIC GRATING IN THE 14.5-16.0-NM WAVELENGTH REGION

The efficiency of an ion-etched laminar holographic grating was measur ed at near-normal incidence in the 14.5-16.0-nm wavelength range. The grating had an electron-beam-evaporated Mo/Si multilayer coating match ed to the grating groove depth. The efficiency peaked at 16.3% in the first inside order at 15.12 nm and 15.0% in the first outside order at 14.94 nm. These are believed to be the highest efficiencies obtained to date from a multilayer-coated laminar grating at near-normal incide nce in the EUV (lambda < 30.0 nm). Zero and even orders were almost co mpletely suppressed. The grating groove efficiency in the first order approached the theoretical limit of 40.5%. (C) 1997 Optical Society of America.