A controller is used for monitoring {HEAD ~ intensity} of {TAIL ~ the beam} of light emerging from the optical switch and for providing a feedback signal to the phase shifters 
of
A controller is used for monitoring { HEAD ~ intensity } of { TAIL ~ the beam } of light emerging from the optical switch and for providing a feedback signal to the phase shifters
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH