In one form {HEAD ~ the detected photoluminescence} is compared to {TAIL ~ detected scattered excitation light} to determine temperature 
is compared to
In one form { HEAD ~ the detected photoluminescence } is compared to { TAIL ~ detected scattered excitation light } to determine temperature
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH