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