by changing {HEAD ~ a voltage} between the second voltage application electrode and {TAIL ~ the second opposing electrode}, a change of focusing state is caused with respect to light that is incident on the second phase changing layer 
between
by changing { HEAD ~ a voltage } between the second voltage application electrode and { TAIL ~ the second opposing electrode } , a change of focusing state is caused with respect to light that is incident on the second phase changing layer
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH