The device scans a subject's eyes, which contains more than 200 identifying marks within the iris alone. Images of the eyes can be uploaded to a national database where it is compared to records.
Some experts believe it's not only faster, but more accurate than checking someone's fingerprints.
Many jails and prisons use the system to make sure inmates who are coming in are who they say they are, and to ensure the wrong people don't get released.
