Retina Scanner or Iris Scanner
A Retina Scanner, sometimes mistakenly referred to as an iris scanner, is a device used for biometric authentication.
Retina scanners map the pattern of blood vessels in an individual's retina and use this pattern to confirm identity.
Each individual's retina scan is unique and retina scanners are quite difficult to fool. However, retina scanning hardware is significantly more complex and expensive than hardware for other kinds of biometric identity checks, and the process of actually providing a retina scan is comparatively intrusive, and significantly interrupts workflows.