(This Idea is more generic than the current category, but one of the alternatives, "Computer:Web:Identity", is just as specific as the "Business:Credit Card:Security" category. We need a more generic "Identity" category somewhere!)
Retinal scans, for uniqueness of personal identification purposes, are widely known to exist. This variation on the theme, however, seeks to close a loophole in the security of existing retinal scanning systems.
In various stories the bad guys kill someone, extract an eyeball, and put it against a retinal scanner. It then allows the bad guys to enter an otherwise-secure location. The scanner needs to check for a living eyeball!
Well, it occurred to me that since the thing actually scanned is the pattern of blood vessels feeding the retinal cells of the eyeball, and since it is known that as the heart pumps blood,there are detectable surges/pulses in the body's arteries, then those pulses should be visible to a higher-resolution retinal scanner, so long as it does more of a video scan, instead of a single-image scan, of the retina. (On the inside of my own arm-elbow, I can see with my own eyeballs pulses of the main arm-artery. The arteries in the eyeballs are more like capillaries, but the pulses should still be detectable.)
The pattern of blood vessels in the retina still needs to match the system record, of course --but If the pulses are not there (or even are very fast due to stress of coercion), then the security system can refuse access to whatever room(s) it guards.-- Vernon, Aug 07 2015 http://www.extremet...and-detail-in-video [2 fries shy of a happy meal, Aug 07 2015] I would be very surprised if this isn't already a thing.If not, the newest programs used to amplify micro-movements would do the trick. [link]-- 2 fries shy of a happy meal, Aug 07 2015 [+] but what's with the penultimate paragraph? Inside of arm-elbow?-- nineteenthly, Aug 07 2015 A simpler technology would be to look for eye- tracking of a moving target, no?-- MaxwellBuchanan, Aug 07 2015 random, halfbakery