In {TAIL ~ a dual focusing optical pickup device}, {HEAD ~ a laser beam} is incident on an optical member via a beam splitter 
In
In { TAIL ~ a dual focusing optical pickup device } , { HEAD ~ a laser beam } is incident on an optical member via a beam splitter
REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH