Tags that are associated with an item such as a person or vehicle are caused to optically flicker out an identifying pattern when triggered by a user or a device at an access point (gate, computer, card reader, or the like). The association of the tag and item can include a physical attachment. The flickering light is analyzed and access is permitted if the data key encoded in the flickers is an authorizing code. A lamp such as a laser or LED is used to create the flickers.