It might appear that projection keyboards are a step towards touch screens where touch of a finger is replaced by a sight of an eye, as described in my previous article. Indeed, in these keyboards fingers don't have to actually touch a button projected by a laser on a flat surface. It is sufficient for a finger to come close enough to the projected button. Sensors would then sense that it is closer to that button than to the others and would trigger the "click" of that button.
But touch screens are not reduced to keyboards. They are much more complex than keyboards. Can lasers project all elements of a touch screen, not a keyboard only ?
Besides current laser projectors are pretty big external devices. They are not suitable for projecting touch screens of smart phones or tablets as they cannot be put inside these devices. Should a technology emerge that would allow tiny lasers to be put inside smartphone and project touch screens from inside out that would make sense.
But even then it would not allow substituting "touching" by staring, as lasers are harmless to eyes. Maximum what can be expected from laser projected screens is eliminating the necessity for a finger to actually touch anything.
Thus, we are still far away from "stare" screens controlled by eye staring into a point rather than by touching it with a finger.