An LC based optical device compensates for {HEAD ~ differences} in optical path lengths of polarization components of {TAIL ~ input beam} 
An LC based optical device compensates for { HEAD ~ differences } in optical path lengths of polarization components of { TAIL ~ input beam }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL