Why can t I see clearly when the cat s eye on the security door has been rubbed with alcohol?

It depends on which brands you buy, many anti-theft doors now have that kind of copper cat's eye, which is the kind that prevents the cat's eye lock picker from unlocking, there is really none, you can only buy one and install it yourself.

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.

Concave lenses. The concave lens is a virtual image with upright and shrinking regardless of the distance. It is mounted on the outside of the door. >>>More

The eye can see bai into a special and precise DU optics. >>>More

Equipped with an anti-theft lock, it can resist abnormal opening under certain conditions within a certain period of time, and has a certain safety protection performance and meets the corresponding anti-theft security level. >>>More