In Sprague’s current prototype, called iOptik, two small projectors mounted on each arm of a pair of eyeglasses cast an image on the inside surface of polycarbonate lenses. Two sets of nanofilters made from minuscule wires embedded in each contact lens permit different light sources to enter the user’s eye. The outer filter lets through unpolarized light from the outside world. The inner filter lets in only light from the projectors, by blocking out light of different wavelengths. This allows the user to see the display image and the outside world simultaneously.
Users will also be able to switch from the see-through mode to a totally occluded mode so they can play a videogame or watch a 3-D movie with a 120-degree field of vision.
iOptik is not alone in the burgeoning field of augmented-reality devices. Other companies, including Google, have AR systems in development, but those displays are far heavier or have a much smaller visual field.
Sprague says his invention will be ready for FDA testing by the spring of 2014, and he is currently in talks with electronics companies interested in licensing it. Innovega recently received funding from Darpa, the Pentagon’s R&D arm, which plans to use iOptik as part of a project aimed at equipping troops with “super vision.” Using iOptik lenses, soldiers could, for example, call up an overhead map of a battlefield while at the same time seeing the real thing right in front of them.