Patent ID: 6540145
Filing Date: 2003-04-01
Classification: G06K

Abstract:
A laser beam projected from an optical code reader along a propagation axis z, for scanning an optical code in a direction x, generally perpendicular to an axis of elongation of features in the optical code, the features extending along a direction y generally perpendicular to the x direction, wherein dimensions of a central peak of the beam in planes perpendicular to the propagation axis increase in both the x and y directions with distance from the code reader, wherein the laser beam is truncated by an aperture in the optical code reader, wherein a change in a y dimension of the aperture changes an x dimension of the central peak of the beam, and wherein the laser beam has a wave front having a deviation W(r) relative to a reference plane generally perpendicular to the propagation axis, the deviation being characterized by:W(r)=&agr;râˆ’&bgr;r2 wherein r is a radial distance from the propagation axis, wherein &agr; is selected to produce a spot of the beam at a minimum scanning distance with a diameter d0 sufficient to permit reading of the code at its highest density, and wherein &bgr; is selected to provide optimum working ranges for codes of different densities.