Patent ID: 8110345

Claim:
A method for producing a pattern on a substrate covered with a photosensitive material, the method comprising: exposing the substrate with a first standing wave interference pattern produced by a superposition of coherent beams of radiation; masking at least a first portion of the substrate; exposing the substrate, subsequent to the masking, with at least a second standing wave interference pattern produced by a superposition of coherent beams of radiation; masking at least a second portion of the substrate; developing said photosensitive material; and wherein the superposition of coherent beams of electromagnetic radiation is formed by sending a single laser beam through a beam expander, reflecting said expanded beam from a first reflecting surface such that a lower portion of said reflected beam strikes the substrate while an upper portion of said beam strikes a second reflecting surface that is perpendicular to said substrate and which reflects said upper portion also onto the substrate, the lower and upper portions now making equal angles with the normal to the substrate and being symmetrically disposed about said normal.