Wiktionary
vision panel
n. A small window in a door which allows people to look through without opening the door.
Usage examples of "vision panel".
Murchison held the overall shape while Conway thought-warped the trailing edges and stabilizer so that it performed a balanced vertical bank just outside the direct-vision panel and headed away from the ship in a long, flat glide.
He spotted it about twenty meters away on the far side of the direct-vision panel.
She forced herself to look through the casualty deck's direct vision panel.
Through them he could see a section of ceiling and, at a crazy angle, the vision panel.
There was a small vision panel on the inner door and she checked, carefully, to make sure there weren't any more orcs in the engineering space.