US 20060022140 A1
| Publication number | US20060022140 A1 |
| Publication type | Application |
| Application number | US 11/140,558 |
| Publication date | Feb 2, 2006 |
| Filing date | May 27, 2005 |
| Priority date | May 27, 2004 |
| Also published as | WO2006085904A2, WO2006085904A3 |
| Inventors | James Connelly, Jeffrey Stillson |
| Original Assignee | L-3 Communications Security And Detection Systems, Inc. |
| Export Citation | BiBTeX, EndNote, RefMan |
| Referenced by (25), Classifications (7), Legal Events (1) | |
| External Links: USPTO, USPTO Assignment, Espacenet | |
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.
DESCRIPTION
This application claims benefit under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 60/575,107, entitled “Method and Apparatus for Detection of Contraband Using Terahertz Time Domain Spectroscopy,” filed on May 27, 2004, which is hereby incorporated by reference in its entirety.
1. Field of Invention
The invention relates to contraband detection systems that use terahertz radiation.
2. Discussion of Related Art
Contraband detection systems are used to inspect items, such as luggage and packages, to detect the presence of contraband (e.g., weapons, explosives and drugs). Contraband detection systems may be used to inspect items at various locations, such as airports, points of entry and secure buildings. Multiple types of contraband detection systems are known, e.g., x-ray inspection systems and explosive trace detection systems.
X-ray inspection systems may inspect an item by detecting radiation transmitted and/or scattered from regions of the item. For example, U.S. Pat. No. 5,600,700 to Krug et al. entitled, “Detecting Explosives or other Contraband by Employing Transmitted and Scattered X-rays,” which is hereby incorporated by reference in its entirety, describes an x-ray inspection device for detecting a specific material of interest using transmitted and/or scattered x-rays. Some x-ray inspection systems determine physical properties of portions of an item under inspection, for example, density and/or atomic number, by detecting transmitted and/or scattered x-rays.
Some inspection systems may use more than one inspection modality to inspect an item (e.g., for multi-level screening). For example, U.S. Pat. No. 5,642,393 to Krug et al. entitled, “Detecting Contraband by Employing Interactive Multiprobe Tomography,” which is hereby incorporated by reference in its entirety, describes an inspection system that uses more than one inspection modality to inspect an item.
A novel inspection system employing terahertz radiation is described below. Terahertz radiation refers to electromagnetic radiation in the range generally between what may be considered microwave and infrared radiation. This range extends from approximately 0.1×1012 Hz to approximately 3×1012 Hz, and is generally not visible to a human. Methods for generating and detecting terahertz radiation are known. For example, U.S. Pat. No. 6,844,552 entitled, “Terahertz Transceivers and Methods for Emission and Detection of Terahertz Pulses Using Such Transceivers,” which is hereby incorporated by reference in its entirety, describes a system for emitting and detecting terahertz frequency electromagnetic pulses.
In a first aspect, the invention relates to a method of inspecting an item that includes a plurality of regions. The method includes detecting terahertz radiation that has interacted with the plurality of regions. The method also includes determining a density of each of the plurality of regions.
In another aspect, the invention relates to a method of inspecting an item that includes a plurality of regions. The method includes detecting terahertz radiation reflected from the item. The method also includes determining a physical property of each of the plurality of regions.
In yet another aspect, the invention relates to an inspection system that includes an inspection region adapted to receive an item under inspection. The system includes a terahertz radiation source located adjacent to the inspection region. The system also includes a terahertz radiation detector located adjacent to the inspection region. The system further includes a controller/processor coupled to the terahertz radiation detector that receives detection information from the terahertz radiation detector and determines, at least partially based on the detection information, density information about the item under inspection.
In a further aspect, the invention is directed to a method of determining the presence of a threat object within an item under inspection. The method includes inspecting the item using a first inspection modality to produce first inspection information. The method also includes detecting terahertz radiation that has interacted with the item under inspection. The method also includes determining second inspection information at least partially based on the detected terahertz radiation. The method further includes determining third inspection information at least partially based on the first and second inspection information
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