Where to buy the cat s eye on the security door

Concave mirrors.

Because, the role of the cat's eye is to use a smaller hole to see a larger range, the flat mirror does not have this effect, and the convex lens will produce a magnifying effect, the image is large, the range is also large, where you can't see a larger range, only the concave mirror has a narrowing effect, the image is small, and the range of seeing is also large. >>>More

What do you want to do, I don't know

Blow the film hot with an electric hair dryer, which is easy to remove, or use hot water.

The "cat's eye" is composed of a concave lens and a convex lens, the objective lens is a concave lens, and the eyepiece is a convex lens, but the focal length of the objective lens is shorter, the focal distance of the eyepiece is longer, and the focal length of the eyepiece should be equal to or greater than the distance between the objective lens and the eyepiece (the length of the cat's eye) and the sum of the focal length of the eyepiece, so that when people look from the inside of the door, they can clearly see the situation outside, and when they look from the outside to the inside, they will not see anything.

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