{HEAD ~ The first mirror} is configured to receive {TAIL ~ a first incident laser beam} from the first end and to reflect a first reflected beam to reflect as a third reflected beam from the third mirror 
is configured to receive
{ HEAD ~ The first mirror } is configured to receive { TAIL ~ a first incident laser beam } from the first end and to reflect a first reflected beam to reflect as a third reflected beam from the third mirror
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL 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 OTH OTH OTH OTH OTH