, the window has a diffractive optical element on {HEAD ~ a surface} of {TAIL ~ the window} closest to the array, the diffractive optical element arranged to partially collimate the light 
, the window has a diffractive optical element on { HEAD ~ a surface } of { TAIL ~ the window } closest to the array , the diffractive optical element arranged to partially collimate the light
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH