Researchers at Pacific Northwest National Laboratory (PNNL) are helping customs agents and other law enforcement officials get a peek inside sealed containers. The laboratory's Acoustical Inspection Device (AID) enables identification of sealed compartments that may contain explosives, illegal drugs, or other types of contraband. The device also allows users to find liquids in sealed containers and measure the level of liquid inside. PNNL's Aaron Diaz, a physicist, says that as it's currently configured, the AID uses ultrasound for detecting pockets and voids in metal containers, gas tanks, and other receptacles in which someone could hide a weapon of mass destruction or kilo of cocaine. The device's sensors transmit ultrasonic pulses and detect return echoes that have bounced off the side of the container. The features and unique characteristics of the return echoes are then compared with a library of material characteristics. "It's all based on a material's properties and the signature we read and compare with the device's onboard database," says Diaz. "It's so sensitive that we can tell the difference between Classic Coca-Cola and Diet Coke." The damping characteristics of wood and other porous materials pose a limitation today, but Diaz says that adjustments could be made in the future. He points out that the Mehl, Griffin, and Bartek Company in Arlington, VA is currently commercializing AID for U.S. Customs agents. A similar version of the device is developed for use along borders in Eastern Europe. For more information, go to www.pnl.gov.