You can acquire the night vision-googles in the start of Chapter 4(I think it is) after you are smuggled in the train to the nazi/comies firefight. When you are dropped out of the train you just need to turn around and walk backward to the end of the tunnel. There is one guard watching, kill him. At the end of the tunnel there is a alcove in the tunnel. There you can open up a box which contain some ammo and the night vision.