Method and apparatus for precisely aligning digital images on motion picture film created by a raster scan recorder

In high-speed raster film recording, a method and apparatus for precise vertical alignment of images to reference perforations without pausing or adjusting the film transport mechanism, and without pausing or adjusting the horizontal beam deflection mechanism. The system (400 and 500, 600 or 700) senses the phase and hence time difference between the occurrence of the Top of Frame signal (upon detecting the reference perforation) and the next Linestart signal (generated each time the horizontal writing beam deflector (506, 606, 706) is in the position to begin writing a new scan line), and in response thereto, vertically deflects the writing beam by optical deflection means (502, 610, 730, 740, 750) up to one-half a scan line in either vertical direction.