{HEAD ~ A scraper mirror} reflects the beams to a thermal imager which reflects {TAIL ~ the beams} to a pair of NaCl beamsplitters 
{ HEAD ~ A scraper mirror } reflects the beams to a thermal imager which reflects { TAIL ~ the beams } to a pair of NaCl beamsplitters
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH