A polarization beam splitter 203 and {HEAD ~ mirrors} 205 and 207 change {TAIL ~ the course} of the light beam towards the inner face of a drum 120 
change
A polarization beam splitter 203 and { HEAD ~ mirrors } 205 and 207 change { TAIL ~ the course } of the light beam towards the inner face of a drum 120
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH