a fully reflecting flat beam dividing mirror which, in the reflectance mode, causes {HEAD ~ approximately half} of such collimated radiation to be reflected by {TAIL ~ the second focusing reflector} toward the sample, and permits substantially the entire post sample radiation to travel from the second focusing reflector to the detector 
to be reflected by
a fully reflecting flat beam dividing mirror which , in the reflectance mode , causes { HEAD ~ approximately half } of such collimated radiation to be reflected by { TAIL ~ the second focusing reflector } toward the sample , and permits substantially the entire post sample radiation to travel from the second focusing reflector to the detector
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL REL REL 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 OTH