Abstract: Various screening systems are disclosed, including a system including a radiation detection component, a toxic chemical detection component, a toxic chemical agent sampling component, a bio-threat detection component, a puffer-based bio-threat sampling component, an explosive detection component, and an X-ray based imager, such that it automatically screens mail for the presence of multiple threat agents, such as chemical, biological, radiological, nuclear and explosive threats. An automated sample arm collects a sample when a sampling substrate contacts a portion of the item of mail while there is relative motion between the automated sample arm and the item of mail. The sample is conveyed to a detector and the sampling substrate is regenerated by heating it.

Abstract: Methods and apparatus for providing a tunable absorption band in a wavelength selective surface are disclosed. A device for selectively absorbing incident electromagnetic radiation includes an electrically conductive surface layer including an arrangement of multiple surface elements. The surface layer is disposed at a nonzero height above a continuous electrically conductive layer. An electrically isolating intermediate layer defines a first surface that is in communication with the electrically conductive surface layer. The continuous electrically conductive backing layer is provided in communication with a second surface of the electrically isolating intermediate layer. The arrangement of surface elements couples at least a portion of the incident electromagnetic radiation between itself and the continuous electrically conductive backing layer, such that the resonant device selectively absorbs incident radiation, and reflects a portion of the incident radiation that is not absorbed.