Patent ID: 6736321
Filing Date: 2004-05-18
Classification: B82Y,G02B,G06K,G07G,H01L,H01S

Abstract:
A planar laser illumination and imaging (PLIIM) based system employing wavefront control methods for reducing the power of speckle-pattern noise within digital images acquired by said system, comprising:a housing having a first light transmission aperture, a second light transmission aperture, and a third light transmission aperture, wherein said first and second light transmission apertures are optically isolated from said third light transmission aperture spatially aligned on opposite sides thereof; a pair of planar laser illumination arrays (PLIAs) mounted within said housing, for producing and projecting a first and second planar laser illumination beams (PLIBS) through said first and second light transmission apertures respectively, so as to produce a composite planar laser illumination beam (PLIB) outside of said housing, and illuminate an object therewith as said object is transported past said first, second and third light transmission apertures; and an image formation and detection (IFD) module mounted within said housing, and having a linear image detection array with a photo-integration time period and image forming optics for providing said linear image detection array with a field of view (FOV) which is projected through said third light transmission aperture, and along which digital images of illuminated portions of said object can be detected, wherein said digital images contain speckle-pattern noise, and wherein said PLIB and FOV are arranged in a coplanar relationship along the working range of said PLIIM based system so that said composite PLIB illuminates primarily within said FOV of said IFD module; and a wavefront control mechanism mounted within said housing, for controlling one or more characteristics of the wavefront of said composite PLIB so as to reduce either the spatial and/or temporal coherence of said composite PLIB prior to its illumination of a selected portion of said object, so that time-varying different speckle patterns are present in said digital images detected at said linear image detection array, whereby said time-varying different speckle patterns are temporally averaged at said linear image detection array during said photo-integration time period so that the power of speckle-pattern noise at said linear image detection array is substantially reduced.