Stocks of the few publicly traded biometrics companies soared Monday. Biometrics systems identify travelers by fingerprints, the patterns in their retinas, their voices or other individual characteristics.Leading biometrics systems include Visionics’ FaceIt, a system that profiles individuals based on 80 facial structures like distance between the eyes, cheekbone formation and the width of the nose bridge; and eye scans, which look at either the distinctive patterns in the blood vessels of the retina at the back of the eye or the unique features of the iris.

Eye-scanning may be the most internationally acceptable form of biometrics, but the facial structure approach may have the advantage of being more easily linked to a database of potential terrorists.