The beam reaches the far end of the hole, and is reflected from {TAIL ~ a surface} located at or adjacent the far end of the hole to illuminate {HEAD ~ the interior} of the hole 
The beam reaches the far end of the hole , and is reflected from { TAIL ~ a surface } located at or adjacent the far end of the hole to illuminate { HEAD ~ the interior } of the hole
OTH OTH OTH OTH OTH 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 OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH