Patent ID: 7790353

Claim:
A method for enhancing photoreactive absorption in a specified volume element of a photoreactive composition, the method comprising: providing a photoreactive composition; providing a source of light sufficient for simultaneous absorption of at least two photons by the photoreactive composition, the light source having a beam capable of being divided; dividing the light beam into a plurality of equal path length exposure beams; focusing the exposure beams in a substantially non-counter propagating manner at a single volume element of the photoreactive composition simultaneously to effect simultaneous absorption of at least two photons by the photoreactive composition and reaction of at least a portion of the photoreactive composition; scanning the photoreactive composition and/or the single volume element relative to each other in at least two directions to form a three-dimensional pattern; and wherein the photoreactive composition is exposed with the single volume element, wherein the single volume element is approximately symmetrical, being formed with a laser intensity such that it has no dimension less than the cross-section of a diffraction-limited spot produced by 800-nm light with a 0.75 NA objective.