The apparatus further includes {HEAD ~ an illumination system} for illuminating {TAIL ~ the interior} of the hole 
for illuminating
The apparatus further includes { HEAD ~ an illumination system } for illuminating { TAIL ~ the interior } of the hole
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH