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...http://www.google.com/patents/US6375074?utm_source=gb-gplus-sharePatent US6375074 - Holographic laser scanner for producing a highly-defined three-dimensional scanning volume having multiple focal regions within which the laser scanlines are spatially confined
