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