Gerald Heine’s stereo microscope uses a field sequential method for generating 3D video. A CRT draws half the screen’s lines with each frame. So, if you send the video from two different cameras on alternating frames you can generate a 3D using shutter glasses. Gerald’s setup uses the sync signal from one camera to control the other. Both video signals are fed into his custom 3D video sync box which combines the frames into a single video feed and also outputs a control signal for shutter glasses.