detection of true threat materials, and the need for operators to clear the equipment before being able to proceed with passenger screening.
The trade-off between technology performance and acceptance by air carriers or the public is a feature common to imaging, nonimaging, and trace-detection technologies. For example, a sharper (i.e., less ambiguous) image could be obtained by increasing observation time, but doing so could add to passenger delays. The intensity of the incident beam could also be increased, but this could lead to increased passenger concerns about exposure to radiation. Similarly, a more aggressive sampling for trace detection could lead to a higher rate of positive identification of explosive materials, at the expense of making the sample-collection phase more personally invasive to the passenger. Ultimately, the performance capability and quality of a passenger screening technology is unlikely to be the limiting factor in its implementation or application. Limitations on the technology will instead be imposed as a result of passenger intolerance for invasion of privacy, delays, or discomfort.