How does a two-way mirror work?
A two-way mirror, also called a one-way mirror by some, is often used to provide one-way observation during a police interrogation or camouflage for a surveillance camera. Television teleprompters also use a two-way mirror to reflect the script towards the performer. This gives the illusion the performer is looking directly at the audience while delivering the lines. Some unscrupulous store owners or hotel managers have also been accused of using two-way mirror technology to illegally spy on their customers or invade a guest’s privacy. The use of two-way mirrors can be very controversial at times. A two-way mirror is not created in the same way as a traditional mirror. A pane of glass used for mirrors of any kind has two separate surfaces suitable for the tinting process known as silvering. The first surface is the outermost layer of the front side. The second layer is directly behind the thickness of the glass, or the “front of the back” as it were. In traditional mirrors, a layer of
For all their mystery, two-way mirrors are actually very simple devices. In reality, any mirror can be made into a two-way mirror; it’s not the glass that makes a mirror two-way, it’s the film on top of the glass. Two-way mirrors have a semi-transparent film (also called a half-silvered surface) deposited onto one side of the glass. This film reduces, but does not eliminate, the amount of light that can travel through the glass. Too much film, and all of the light is reflected, and you have a regular mirror. Most two-way mirrors have just the right amount of film so that half the light comes through and half the light is reflected. The real trick, however, has to do with the lighting in two adjoining rooms that share the mirror. As you’ll notice on television shows that use two-way mirrors, one room is brightly lit and one room is dim. In the room with plenty of light (i.e. the room with the suspect), there is so much light that even though half of the light travels through the mirror,
A two-way mirror generally takes advantage of the fact that one side is more brightly lighted than the other – like looking out of a window from a brightly lighted room into the outdoors at night. You can’t see out, but others can potentially see in. Similarly, a two-way mirror’s coating enhances this effect, reflecting light from the brightly lighted side, but allowing those on the more dimly-lighted side to see through.
by two-way mirror, I mean something that you can see through like glass from one side (although it appears somewhat shaded) and from the other side looks like a normal mirror. The kind used to hide security cameras. I don’t know if two-way mirror is the correct name for it, which may be why I can’t find anything on the www. I’d like to turn the glass on a french door into a two-way mirror and install it for my front door. I’m trying to find out wether mofifying the glass on an existing door, or building the door with mirrors would be more cost-effective.
It works like window tint. A person inside the room looking out has no light in there. Now the people in the room looking at a mirror has a light on which helps the reflective properties. Some two way mirrors are cheap film which can be seen through from the opposing side if you reverse the lights.
