Electro-optical reader with improved laser intensity modulation over extended working range
AssigneeSymbol Technologies, Inc.
InventorsIgor Vinogradov, Vladimir Gurevich, David Tsi Shi, Dariusz J. Madej, Mehul M. Patel, Edward Barkan, Heng (Jade) Zhang
Life of this patent
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Abstract
The combination of a rooftop optical element and a soft edge aperture stop, as well as the introduction of a negative spherical aberration in a positive focusing lens, improve working distance and depth of focus in both moving beam and imaging readers for electro-optically reading indicia such as bar code symbols, especially for close-in symbols, and moreover tend to reduce undesirable light intensity modulation in the beam profile thereby improving reader performance.
Claims9
An optical assembly in a system for electro-optically reading indicia extending along mutually orthogonal directions by sweeping a laser beam in a scan across the indicia, comprising:
- a) an asymmetric optical element for extending working range in which the indicia is read with concomitant undesirable laser intensity modulation, the element having an optical axis and a pair of lens surfaces for focusing the laser beam to multiple focal points along the optical axis, the lens surfaces meeting along a line that intersects the optical axis and that has a length dimension extending along one of the directions, the element having a width dimension extending along the other of the directions and being independent of the length dimension;
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- b) an aperture stop for reducing the undesirable laser intensity modulation with concomitant reduction in the working range, the aperture stop including an optical aperture, and a support bounding the optical aperture along a border that shapes the optical aperture with variable dimensions along both of the directions along which the indicia extends, the optical aperture having a plurality of light-passing areas spaced apart along the border, and the support having a light-obstructing area between the light-passing areas along the border.
An optical assembly in a system for electro-optically reading indicia extending along mutually orthogonal directions by imaging laser light scattered from the indicia over a field of view, comprising:
- a) an asymmetric optical element for extending depth of focus in which the indicia is read with concomitant undesirable laser intensity modulation, the element having an optical axis and a pair of lens surfaces for imaging the laser light from multiple image points along the optical axis, the lens surfaces meeting along a line that intersects the optical axis and that has a length dimension extending along one of the directions, the element having a width dimension extending along the other of the directions and being independent of the length dimension;
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- b) an aperture stop for reducing the undesirable laser intensity modulation with concomitant reduction in the depth of focus, the aperture stop including an optical aperture, and a support bounding the optical aperture along a border that shapes the optical aperture with variable dimensions along both of the directions along which the indicia extends, the optical aperture having a plurality of light-passing areas spaced apart along the border, and the support having a light-obstructing area between the light-passing areas along the border.
Dependencies are inferred from the claim text.