Patent ID: 7528380
Filing Date: 2009-05-05
Classification: B82Y,G02B,G02F,G03F,H01J

Abstract:
1. A method for focusing a beam to provide a spot size smaller than that obtained using diffractively limited conventional techniques, the method comprising: directing a primary beam along a primary beam axis to impinge on a target at a primary beam spot, the minimum attainable size of which is limited by diffraction effects; generating an energy-depleted beam having a depleted level of irradiance relative to its wave intensity; converting the energy-depleted beam to a modified energy-depleted beam having an annular cross section; focusing and directing the modified energy-depleted beam along the primary beam axis in such a manner as to converge and intersect with the primary beam, to form a tapered annular region in which the volumetric spaces occupied by the primary beam and the modified energy-depleted beam overlap; and adjusting the energy-depleted beam in wave intensity and phase to provide in the tapered annular region an energy-depleted beam that is equal in wave intensity to that of the primary beam and 180 degrees out of phase with the primary beam; wherein the primary and modified energy-depleted beams destructively interfere in the tapered annular region and the primary beam is effectively focused at the target to a spot size smaller than the primary beam spot size.