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