It is purposeful to connect {HEAD ~ an adjusting unit} to {TAIL ~ the transmitting} and receiving optics, by means of which the transmitting and receiving optics may be trimmed and adjusted with regard to each other 
It is purposeful to connect { HEAD ~ an adjusting unit } to { TAIL ~ the transmitting } and receiving optics , by means of which the transmitting and receiving optics may be trimmed and adjusted with regard to each other
OTH OTH OTH OTH OTH HEAD HEAD 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 OTH OTH OTH OTH OTH OTH