Abstract: A multi-level contraband detection system. At a first level, the system obtains volumetric information about an item under inspection. The volumetric information provides a basis for identifying suspect objects in the item under inspection and their locations. The location information is expressed in a first coordinate system relative to the device used for first level scanning. When first level scanning identifies a suspicious object, the item under inspection is passed to a second level scanner that can take further measurements on the suspicious objects. The second level machine is controlled in a second coordinate system. A translation between the two coordinate systems is obtained by registering a multi-dimensional image obtained at the first level with positioning information obtained at the second level. Registration is performed using a coarse and then a fine registration process for quick and accurate registration.

Abstract: An inspection system and methods for inspecting items using terahertz radiation that may be used to detect contraband (e.g., explosives, weapons and drugs) within items under inspection. Terahertz radiation may be transmitted through and/or reflected from an item. The density and/or a physical property of one or more regions within an item may be determined. Terahertz radiation may be used to inspect surface regions of an item and/or other regions of an item. Terahertz radiation may used in combination with and/or in addition to another inspection modality.