Optical scanner having multiple, simultaneous scan lines with different focal lengths

DETAILED DESCRIPTION The present invention improves scanner reading performance by increasing the effective density of a scan pattern.
Two or more scan lines are generated simultaneously with each line being focussed at a different point in space.
One line in one pattern might be focussed at a point far from the scan window while the corresponding, simultaneously generated line in the other scan pattern is focussed at a point nearer the scan window.
The total number of scan lines can be multiplied without sacrificing the length of individual scan lines.
A scanner constructed in accordance with the present invention includes means for generating a plurality of light beams, each of which has a distinctive characteristic.
The scanner further includes means for focussing each of the beams at a different predetermined focal point.
Beam deflecting means are included in the path of the plurality of light beams for generating simultaneous focussed scan beams.
Light reflected from an object being scanned is detected to generate a single signal which varies in accordance with the total reflected optical energy.
The scanner further includes means for separating the single signal into a plurality of a constituent signals as a function of the distinctive characteristic of each of the generated light beams.
Each constituent signal varies as a function of the reflected optical energy attributable to a given one of the plurality of light beams.