Patent ID: 6633433
Filing Date: 2003-10-14
Classification: G06K,Y10S

Abstract:
In a scanner for electro-optically reading indicia located within a working range of distances relative to the scanner, a beam shaping system for extending the working range, the system comprising:a) a laser for producing an asymmetric laser beam; b) a beam shaper for optically shaping the asymmetric laser beam to form an axially symmetric Gaussian beam; c) an aperture stop for truncating the symmetric Gaussian beam to form a truncated Gaussian beam having a cross-sectional area; and d) a Bessel filter for optically modifying the truncated Gaussian beam to form a composite Bessel-Gaussian beam having a non-diffracting Bessel beam component for reading indicia at near distances relative to the scanner within the working range, and a diffracting Gaussian beam component for reading indicia at far distances relative to the scanner within the working range, the Bessel filter having a central circular portion corresponding in area to the cross-sectional area of the truncated Gaussian beam.