The design and fabrication of large-area, high-efficiency metallic gra
tings for use in high-power laser systems is described. The gratings e
xhibit a diffraction efficiency in excess of 95% in the m = -1 order (
Littrow mount) and have a high threshold for laser damage. Computation
s and experimental measurements are presented that illustrate the effe
ct of grating shape and polarization on efficiency. A simple theory fo
r optical damage to metallic diffraction gratings is developed and com
pared with experimental measurements of the laser-damage threshold ove
r the pulse range from 400 fs to > 1 ns.