The printed circuit board may include an embedded optical waveguide and a first optical window extending from the optical waveguide to {HEAD ~ a first surface} of {TAIL ~ the printed circuit board} 
The printed circuit board may include an embedded optical waveguide and a first optical window extending from the optical waveguide to { HEAD ~ a first surface } of { TAIL ~ the printed circuit board }
OTH 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 TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL