The other part of the incident beam is refracted and transmitted through the optical member and then totally reflected by {HEAD ~ the reflecting member} to return to {TAIL ~ the optical member} 
to return to
The other part of the incident beam is refracted and transmitted through the optical member and then totally reflected by { HEAD ~ the reflecting member } to return to { TAIL ~ the optical member }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL