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