An apparatus and method for stereoscopic 3D image projection and viewing using a single projection source, alternating polarization, and passive eyewear. This approach is applicable to frame sequential video created using existing 3D graphics APIs, as well as other video signal formats, and is compatible with existing digital light processor (DLP) technology for both front and rear projection systems. An alternating polarizer in the form of a magnetomechanically resonant polarizing filter actuator is used to modulate the projected image. A preferred embodiment enables an existing DLP projection system to be enhanced with 3D capability.