BARCELONA, Spain — Fujitsu today announced an iris detection system for smartphones, and it’s just one of three companies we’ve seen here that are working on the technology.

On the Fujitsu prototype, the user can look at the device’s screen, and the device reads the user’s iris instantaneously. Once the user is recognized, the smartphone is unlocked. The iris is the colored ring around the pupil of the eye.

Some people here say iris detection is more accurate and more secure than fingerprint scanners or passwords.

One executive told me that there are already hacks enabling bad guys to detect, steal, and copy fingerprint scans. With 3D iris recognition this is very hard, because the camera takes many images of the iris and makes sure that the iris is moving, and is not just a printout of the user’s eyes, one person explained.

The iris scanning technology could come in very handy for authenticating mobile payments. It might also be used by enterprises to control access to buildings and resources.

In the Fujitsu prototype, infrared light detects the iris pattern. Movements of the smooth muscle of the iris make human eye openings larger or smaller, adjusting the amount of light that enters the retina.

Iris authentication technology discerns a person’s identity by identifying those patterns, which are unique for each individual, much like a fingerprint.