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