Line and space patterns have been fabricated in Si with periods as small as 1.3 mu m using a double patterning technique and an optical direct write tool. The pattern density of a single lithography step is shown to be limited by the proximity effect and that gratings with periods smaller than about 2.0 mu m are beyond the resolution of the 405 nm wavelength laser direct write tool employed in these experiments. The lithography-etch-lithography-etch technique, which includes a highly selective reactive ion etch step, provides a robust way to create 4 mm long gratings of 1.5 mu m period. Variations in this two step lithography process limit the practical minimum pitch for long gratings to about 1.4 mu m.