I posted a query about night vision goggles a few weeks ago and got some great replies I have a question about the one by son of sand

In your reply to my post a few weeks about night vision goggle you said about adding a +diopter to the eye piece..I got my eye clops but am some what mystified about how I would add any thing to the eye piece. Were you referring to the square viewing window or of taking the assembly apart. There are 6 screws that look like they hold the front assembly together. But before I tear apart a band new toy I would like to know what I am doing