Patent ID: 7277604

Claim:
An apparatus for treating a substrate sensitive to electromagnetic radiation, comprising; a) a first mask for conditioning a first beam of electromagnetic radiation and producing a first conditioned beam of electromagnetic radiation; b) a second mask for conditioning a second beam of electromagnetic radiation and producing a second conditioned beam of electromagnetic radiation; the first and the second conditioned beams of electromagnetic radiation being characterized in that, when they are directed toward the substrate sensitive to electromagnetic radiation, a treatment area of the substrate sensitive to electromagnetic radiation is exposed to electromagnetic radiation, the treatment area including: a first portion exposed to only one of the first and the second conditioned beams of electromagnetic radiation; and a second portion exposed to both the first and the second conditioned beams of electromagnetic radiation to create an interference pattern over the second portion; the first and the second conditioned beams of electromagnetic radiation inducing an index of refraction change in the substrate sensitive to electromagnetic radiation, the index of refraction of the substrate sensitive to electromagnetic radiation being modified differently over the first portion than over the second portion, the index of refraction being altered substantially uniformly over the first portion, the index of refraction being altered in a non-uniform manner over the second portion.