{TAIL ~ The interference filter} has {HEAD ~ two metal reflective films}, at least one of which is semi transparent 
{ TAIL ~ The interference filter } has { HEAD ~ two metal reflective films } , at least one of which is semi transparent
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH