By applying theory related to light intensity and manufacturing mirrors, humans have created two-way mirrors that serve in many fields.
Surely, you’ve seen two-way mirrors appear in interrogation rooms on film. These special mirrors allow people from the outside to see the space inside, to observe the suspect’s state, but people from the inside cannot see outside.
So why are these two-way mirrors able to do so? The answer will be explained in this article.
This special mirror allows people from the outside to see the space inside, but people from the inside cannot see outside.
According to Wonderful Engineering, a normal mirror must undergo a mirror coating process, then coated with a reflective material such as silver, tin, nickel or aluminum. The front panel is a transparent glass panel, a copper layer to prevent metal oxidation and a protective layer of reflective coating.
When light enters the glass and hits the metal surface, the light ray is reflected back. That’s also why you can see your own reflection when you look in the mirror.
However, two-way mirrors also use this metal layer but are thinner than ordinary mirrors. The coating of reflective molecules covers half of the total mirror surface area and the other half allows light to pass through.
Working principle of double-sided mirror.
This feature explains why, you can see that the space in the interrogation room is always lit up with the condition of the opposite room so that the space is as dark as possible, avoiding light from passing through the interrogation room.
Double-faced mirrors we often see in movies.
Two-way mirrors work on the principle of light intensity . If the light intensity on both sides of the glass is the same, the mirror will look like a regular piece of glass. But when the light is concentrated on one side and the other side is dark, the glass becomes a mirror to the person in the well-lit space. This phenomenon is quite obvious when you try to look out the door at night but only see the light in the house more reflected.
There is a trick to distinguish a two-way mirror from a regular mirror quite easily. Place your finger on the mirror surface. If you see a gap between your fingertip and the internal reflection, it’s a regular mirror. But if your fingertips touch, you may be looking in a two-way mirror and are at high risk of being tracked.
If your fingertips touch, you may be looking at a two-way mirror.
Two-way mirrors have a wide range of applications, particularly in the interrogation, scientific research, security surveillance or special effects markets.