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