{TAIL ~ a laser light source} for transmitting a laser beam which is disposed in {HEAD ~ the housing} 
{ TAIL ~ a laser light source } for transmitting a laser beam which is disposed in { HEAD ~ the housing }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD