Easy Projection of Stereo Movies

A new method is described for showing color stereo movies with arbitrary movie projectors by the means of a small portable adapter. The beam from an ordinary movie projector is passed through a linear polarizer followed by a crystal which rotates the angle of polarization under voltage control, so that alternating left and right images and polarized 90 degrees apart. A photodiode and a sensing circuits synchronize the polarization shift to the flicker of the projector shutter. The adapter is small, self contained, and needs only be placed in the path of the projected beam. (Author)