The quarter wave plate can be positioned such that {TAIL ~ the direction} of the slow axis of {HEAD ~ the quarter wave plate} and the S polarization direction are generally parallel 
The quarter wave plate can be positioned such that { TAIL ~ the direction } of the slow axis of { HEAD ~ the quarter wave plate } and the S polarization direction are generally parallel
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH