I thought that you would be interested to read this report from a man who is a deeply experienced and practical electronics engineer. I have met him and followed his writing for many years. Peter Cochrane really does know what he is talking about. He is a frequent traveller of high magnitude.
In this item he reports on why he has not joined the Iris Scanning option at some UK airports. Naturally, I am only pasting a small part of the item from Silicon.com
http://comment.silicon.com/petercochrane/
The traveller going through the iris scan enters the booth with full confidence. Then the 'dance of the immature technology' begins. Move closer, move to the left, stand further back, look up, look down and so on. The traveller is then asked to leave the booth, re-enter and start again. This dance is repeated until an attendant arrives to reboot the technology. By this time I'm at the front of the long line and on my way home.
Just what is going on here? More than 10 years ago I had this technology in my lab and it performed faultlessly. Integrated mechatronics would automatically scan your face, locate your eye, focus and take a picture. The electronic analysis was more or less instantaneous. So why all the fuss at Heathrow?
There is more before and after this extract and I think he is probably correct.