Mathieu-Gaussian beam for optical scanners
AssigneeSymbol Technologies, Inc.
InventorYajun Li
Life of this patent
Estimating the term…
Abstract
A laser beam having a Mathieu-Gaussian intensity profile is provided, which may be used for various optical scanning applications at various scanning distances. The Mathieu-Gaussian beam exhibits a zone of illumination characterized by a central spot and side lobes centered on an axis of elongation of the zone of illumination. The zone of illumination may be used with scanners that either generate a single scan line, or another omni- or multi-directional raster pattern, to scan symbols over large variations of distance.
Claims18
An apparatus for generating a laser beam and for scanning a target optical code, said apparatus comprising:
- a source for generating a laser beam having a Gaussian irradiance profile;
- a Mathieu filter in an optical path of the laser beam and configured to produce an apodized Mathieu beam of coherent light;
- an activation means for activating the source for generating the laser beam and propagating the laser beam towards the Mathieu filter;
- and
- means for scanning the apodized Mathieu beam across the target optical code by generating at least two scan lines across the target optical code.
An optical code reading apparatus comprising:
- means for generating a beam of laser light;
- means for introducing Gaussian apodization to the beam;
- means for filtering the beam to produce a Mathieu beam having confocal symmetry and an extended working range compared to the beam of laser light, said Mathieu beam exhibits a raster scan pattern in a portion of the working range;
- and
- means for reflecting a beam indicative of the Mathieu beam reflected by an optical code towards a photo detector for detecting at least one line of the optical code.
An optical code scanning system, comprising:
- a laser beam assembly for providing a Mathieu-Gaussian laser beam configured to produce an illumination pattern with a central spot and at least one pair of side lobes, wherein a center scan line is created by the central spot and a top and a bottom scan line are created by the at least one pair of side lobes, and wherein an optical code is scanned using at least one of the scan lines;
- and
- a photo detector for detecting reflected light from the optical code indicative of at least one of the center, the top and the bottom scan lines for reading at least one line of the optical code.
An optical code reader comprising a laser beam source for generating a laser beam for scanning a target optical code, the laser beam being an apodized Mathieu beam having a central spot and at least one pair of side lobes which define a zone of illumination which zone is elongated in a direction that is generally perpendicular to a direction in which the target optical code is scanned and has an aspect ratio selected in accordance with the anticipated dimensions of target codes to be read by the optical code reader, wherein the central spot and the at least one pair of side lobes are arranged to provide at least two scan lines over the target optical code.
A method for designing a scanning laser beam source for an optical code reader for scanning a target optical code in which a laser diode, optical system and aperture are selected for producing a Gaussian-Mathieu beam having a central spot and at least one pair of side lobes defining a zone of illumination which is relatively constant through the working range of the optical code reader, and which zone of illumination is elongated having an aspect ratio selected in accordance with the anticipated dimensions of target codes to be read by the code reader, wherein the central spot and the at least one pair of side lobes are arranged to provide at least two scan lines each capable of independently scanning the target optical code.
Dependencies are inferred from the claim text.