WO/2008/005724 is referenced by 2 patents.
An optical identification tag comprising a retroef lective layer and a light encoding layer positioned over the retroref lective layer is affixed to a license plate of an automobile 110. A transceiver 500 is depicted illuminating the automobile 110 with a laser beam 130. A structured light pattern 140 is returned from optical identification tag 200 back to transceiver 500. Transceiver 500 may decode information encoded in the structured light pattern returned from tag 200.