This illumination follows a path through the objective toward {TAIL ~ the sample}, and again, after reflection, through the objective toward {HEAD ~ the detector} 
This illumination follows a path through the objective toward { TAIL ~ the sample } , and again , after reflection , through the objective toward { HEAD ~ the detector }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD