The iris scanning recognition method uses the unique patterns of the iris of the eye (the colored area that surrounds the pupil). A digital camera uses both visible and near-infrared light to take a clear, high-contrast picture of a person’s iris, a process that does not require physical contact with a scanner. The device then analyzes the patterns in the iris and translates them into a mathematical expression – the most detailed of any biometric technology. The iris is a visible but protected structure, and it does not usually change over time, making it ideal for biometric identification. Like thumbprints, no two iris blueprints are alike, even among identical twins.

Comparing irises against a database can be done quickly and with a high level of accuracy. The technology is not intrusive on the individual (unlike older techniques that scanned the inner blood vessels of the retina) and can be used even in the presence of eyeglasses and contact lenses. Research suggests that a person’s retina can change with age, while an iris remains intact, and usually people’s eyes remain unchanged even after eye surgery. Blind people can use iris scanners as long as their eyes have irises. Iris recognition has also been demonstrated to work with individuals from different ethnic groups and nationalities. However, for people affected with diabetes, the eyes sometimes are affected by the disease, resulting in changes to the iris.

Iris scanning devices have been used in personal authentication applications for several years. Systems based on iris recognition have substantially decreased in price, and this trend is expected to continue. Because iris scanning is quick and highly accurate, it is particularly effective for perimeter and access control. Iris scanning is becoming more popular in correctional facilities as well – several facilities, including Lancaster County and York County prisons in Pennsylvania and Sarasota County Detention Center in Florida, use iris scanning technology as part of their release procedures.