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