The method may further include filling a space between the first optical window and {HEAD ~ the second optical window} with {TAIL ~ a filler} 
The method may further include filling a space between the first optical window and { HEAD ~ the second optical window } with { TAIL ~ a filler }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL