{TAIL ~ A modulated laser beam} is scanned across the object to create {HEAD ~ a plurality} of spots which are viewed by a pair of well matched receivers 
{ TAIL ~ A modulated laser beam } is scanned across the object to create { HEAD ~ a plurality } of spots which are viewed by a pair of well matched receivers
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH