{HEAD ~ The transducer} produces {TAIL ~ an output electrical signal} proportional to the extent to which the third laser beam energy is absorbed by the propane gas 
produces
{ HEAD ~ The transducer } produces { TAIL ~ an output electrical signal } proportional to the extent to which the third laser beam energy is absorbed by the propane gas
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH