Flat window - The structure of ordinary mirror and single mirror. Ordinary mirrors are made of silver plated on glass. The same is true for one-sided mirrors, but only half of them are plated when silver is plated. How can "half" be plated? The method is a bit ingenious: the silver is so thin that half of the light can pass through and the other half is reflected back. In actual use, the prisoner will face the mirror and be in a room with strong light. Because there is enough light and more reflected light, the prisoner will see his image in the mirror. At this time, the witness stood on the other side of the mirror, in a very weak room. Although part of the light in the witness room can also pass through the single-sided reflector, because the light intensity is very low, the prisoner can not see the witness, but can only see his own image. It's as if we can't see fireflies in the strong light of the street lamp, because the weak light from the fireflies is covered by the light of the street lamp.
