a substrate capable of transmitting {TAIL ~ visible light} and having a pair of {HEAD ~ opposing surfaces} 
a substrate capable of transmitting { TAIL ~ visible light } and having a pair of { HEAD ~ opposing surfaces }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD