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