{HEAD ~ The laser beam} scans {TAIL ~ the output medium} and is modulated in accordance with the image to be formed 
{ HEAD ~ The laser beam } scans { TAIL ~ the output medium } and is modulated in accordance with the image to be formed
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH