{HEAD ~ Air} travels through said tube and passes through a plurality of holes along the length of the tube in {TAIL ~ the general direction} of the area where the laser beam strikes the workpiece 
passes in
{ HEAD ~ Air } travels through said tube and passes through a plurality of holes along the length of the tube in { TAIL ~ the general direction } of the area where the laser beam strikes the workpiece
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH