a first focusing reflector which directs source provided {HEAD ~ radiation} to the sample in {TAIL ~ the transmission mode} 
a first focusing reflector which directs source provided { HEAD ~ radiation } to the sample in { TAIL ~ the transmission mode }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL