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