| 摘要 |
A holographic laser scanner for scanning bar code symbols, in which a plurality of scanning planes are projected through a plurality of different focal regions in order to provide, at each such focal region, a plurality of scanlines that are substantially confined within the highly-defined 3-D scanning volume of the holographic laser scanner. This remarkable capability of the system ensures that the scanlines of the holographic scanner extend only where scanning is required (e.g., within the highly-defined 3-D scanning volume). This avoids scanning regions of space where bar code symbols are known to not be present, or collecting scan data from such "empty" regions of space. By virtue of the present invention, the highly-defined 3-D scanning volume of the holographic laser scanner can be easily positioned above a doorway, conveyor belt, loading dock or the like where objects bearing bar code symbols are expected to pass. |
