OPTICAL SCANNER FOR READING BAR CODES DETECTED WITHIN A LARGE DEPTH OF FIELD

Optical scanner for reading bar codes scanned by focussed scan lines having different focal lengths where at least one of the scan lines is small relative to irregularities of the surface on which the label (10) appears. The scan lines are generated using a holographic disk (18) so as to have a predetermined focal length and focal zone. The focal zone of each generated scan line overlaps the focal point of at least one adjacent scan line. Any bar code label (10) which might be scanned by a beam so small that it would be degraded by surface scatter noise is also scanned by a slightly larger beam. The slightly larger beam "averages out" the surface scattering noise to produce a smoother or cleaner return signal.