the present invention is directed to a system and methodology in which the stepper motor of an optical scanning device is replaced by a dc motor which receives feedback information from an extended photodetector used in the scanner , or a proximately close second photodetector . the photodetector of current scanners may be extended to read a margin marking located on , or attached to , the scanner body and the resolution of the extended portion , or separate photodetector , may be increased to accurately capture positioning information . the photodetector of the present invention detects the margin marking , typically located outside of the document scanning area , to determine positional information which is used by the processor to accurately determine position .