Beam shaping for optical scanners
AssigneeSymbol Technologies, Inc.
InventorsLeonard Bergstein, Emanuel Marom, Yajun Li, Joseph Katz
Life of this patent
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Abstract
A beam generator, or beam shaping system, for example for use in an optical scanner, creates a non-Gaussian beam which provides improved indicia-reading characteristics. In one embodiment, diffractive optical elements are used to create a Bessel-Gaussian scanning beam, which comprises a coherent combination of a Gaussian beam and a Bessel beam.
Claims13
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.
In a method of electro-optically reading indicia located within a working range of distances relative to a scanner, a method of extending the working range, the method comprising the steps of:
- a) producing an asymmetric laser beam;
- b) optically shaping the asymmetric laser beam to form an axially symmetric Gaussian beam;
- c) truncating the symmetric Gaussian beam to form a truncated Gaussian beam having a cross-sectional area;
- d) optically modifying the truncated Gaussian beam with a Bessel filter 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;
- and
- e) matching the cross-sectional area of the truncated Gaussian beam to a central circular portion of the Bessel filter.
Dependencies are inferred from the claim text.