METHOD OF AND APPARATUS FOR GENERATING A LIGHT BEAM

摘要

An apparatus for generating a light beam with an extended depth of focus includes a binary phase mask (4) that generates a diffraction pattern including bright main ring and two side-lobe rings, an annular aperture mask (10) that passes only part of the diffraction pattern, and a lens (14) that causes the light passing through the annular aperture (10) to converge towards and cross the optical axis (2). Where the converging light crosses the optical axis, constructive interference takes place, generating a light beam (36) that has an extended depth of focus.