the optic fiber end surface is oriented at an angle of {HEAD ~ 15°} to {TAIL ~ a normal plane} of the optic fiber center axis 
to
the optic fiber end surface is oriented at an angle of { HEAD ~ 15 ° } to { TAIL ~ a normal plane } of the optic fiber center axis
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH