A display apparatus includes an image source, an eye position detector, and {TAIL ~ a combiner}, that are aligned to {HEAD ~ a users eye} 
A display apparatus includes an image source , an eye position detector , and { TAIL ~ a combiner } , that are aligned to { HEAD ~ a users eye }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD