The generator comprises an envelope and two mirrors defining a resonant cavity, in which is maintained {HEAD ~ a monolithic wave guide} with {TAIL ~ a capillary} 
with
The generator comprises an envelope and two mirrors defining a resonant cavity , in which is maintained { HEAD ~ a monolithic wave guide } with { TAIL ~ a capillary }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL