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