| 摘要 |
<p>In a holographic scanning system for scanning a bar coded label (42), light beams from a laser (20) are directed towards a set of hologram members (34a-34e) located on a rotating disk (30) in which each hologram member will generate an individual scan beam having a slightly different focal length and direction angle from that of the other hologram members. Each of the scanning beams is directed at a plurality of mirrors (36a-c, 38a-c) which reflect the beams in the form of a scanning pattern in a scanning area through which the coded label (42) on an article will pass. Each of the scanning beams is projected in an overlapping relationship on the scanning area, thereby providing an enhanced depth of focus enabling a more effective reading operation. The light reflected from the bar coded label is collected by the hologram members (34a-34e) for collimating the reflected light beams. The collimated light beams are directed at a lens member (46) which focuses the received light beams on a photodetector (48) for use in reading the bar coded label.</p> |
