Vascular pattern recognition

Overview
Researchers have determined that the pattern of blood vessels is individual-specific and does not change over time. Vascular pattern recognition is a fairly new biometric technology.

How it works
Near-infrared rays of light generated from a bank of light emitting diodes (LEDs) penetrate the finger or hand and are absorbed by the hemoglobin in the blood. Veins, and other areas in which the rays of light are absorbed, appear as dark areas which are then used to construct patterns. These pattern are then compressed and digitized so that it can be registered as a template. The vein pattern and the template can be compared by means of a pattern-matching technique.

Source

 * NSTC Subcommittee on Biometrics and Identity Management, Privacy and Biometrics: Building a Conceptual Foundation 20 (Sept. 15, 2006) (full-text).