Privacy Enhanced Computer Display
From the Mitsuibshi Research Laboratories:
The privacy-enhanced computer display uses a ferroelectric shutter glasses and a special device driver to produce a computer display which can be read only by the desired recipient, and not by an onlooker. The display alternately displays the desired information in one field, then the inverse image of the desired information in the next field, at up to 120 Hz refresh. The ferroelectric shutter glasses allow only the desired information to be viewed, while the inverse image causes unauthorized viewers to perceive only a flickering gray image, caused by the persistence of vision in the human visual system. It is also possible to use the system to “underlay” a private message on a public display system.