{TAIL ~ a detecting means} for receiving and detecting {HEAD ~ beams} which are incident on and reflected by the beam splitter after being reflecting from the optical disc, 
{ TAIL ~ a detecting means } for receiving and detecting { HEAD ~ beams } which are incident on and reflected by the beam splitter after being reflecting from the optical disc ,
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH