What’s the principle behind two way mirror and how can one detect it?

Question

i mean, how does it work. From one side you see your reflection and from other side you can see through it, how?

Answer 1

Regular glass is simply coated with a reflective mirror looking sheet called mirropane. (trade name). . Your answers can be found in theis website
Some companies in the window-glass and mirror trade call them "two-way mirrors" and some call them "one-way mirrors" — don't ask me why; there seems to be no distinction between the two names. They both refer to a product known as Mirropane. Promotional literature from the LOF Architectural Specialty Glass company states that the product registered under the name "Mirropane E.P. Transparent Mirror" is "formed using LOF's patented chemical vapor deposition process on 1/4" Grey tint glass." As to exactly how that works or even what reflective metal is involved, it seems to be a trade secret, although the good folks at Morehouse Glass in Portland, Oregon suggest that tin or nickle are the likeliest choices.
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Here are some other ways to identify Mirropane from an ordinary, second-surface mirror.

This from William Beaty, electrical engineer, Seattle: "... simply turn the lights off in [the] room, then place a bright flashlight against the mirror surface. If there is a hidden chamber behind the mirror, the flashlight will illuminate it, and since you're in a darkened room, you'll see the hidden chamber."

A deputy from the Washington County Police Department in Oregon concurs, and suggests that even a pen-light will work for this test, though not nearly as well. He further suggests that, if you are in a room (such as a changing room) where you cannot turn off the lights on your side, if you hold your eyes near to the glass surface and cup your hands around them on either side to eliminate most of the light from your visual field, you ought to be able to see through the treated glass, as Mirropane will permit about a 12 percent passage of light (from the lit side to the hidden chamber, if there is one).

Douglas Brown, a part-time field researcher and writer who also works for Powell's Books, Inc. in Portland, Oregon, has some clever advice to share. He makes the point that there is a clear auditory difference between Mirropane and regular mirrors, because of how they are installed. Rap on the surface with your knuckle or fingernail, he says, and in most situations you'll be able to hear the difference in the sound produced. Ordinary mirrors have backing material which will dull the sound, while windows have open air behind them and will reverberate more.

Answer 2

I believe you are asking about a one way mirror, but it doesn't really matter what you call it. You're referring to a window between two rooms that is not 100% reflective. A small amount of light can pass through the mirror.

In order for it to work, the room where the observer is must be darker than the room where person being observed is.

Think of those large mirrored office buildings. Notice how during the day, you can't see inside but at night you can. It's the same principle.

It's difficult to detect, but you can try by turning off the lights in the room and look at the mirror. Another way is to try to get a look at behind the mirror. Is it just hanging or is it permanently fixed to the wall? If it's permanently fixed to the wall, be suspicious. Now days cameras are so small that it's easy to place one behind a mirror.

Hope this helps.

Answer 3

A two way mirror is so that the person on the unmirrored side can see you, but you (on the mirrored side) cant see them. Aparently the best way to tell is to put your finger on the mirror, if there is a space between your finger and the reflection it is a normal mirror, if there is absolutely no space between your finger and the reflection it is a two way. Try it at home, there should be a gap between your finger and the reflection.
Otherwise you can try cupping your hands around your eyes to keep as much light out as possible and try to look through the mirror!

Answer 4

holy crap you're hot!

A one-way mirror reflects some percentage of the light and lets some other percentage pass. It is a sheet of glass coated with a layer of metal only a few dozen atoms thick, allowing some of the light through the surface (from both sides). It is used between a dark room and a brightly lit room. Persons on the brightly lit side see their own reflection - it looks like a normal mirror. Persons on the dark side see through it - it looks like a transparent window. It may be used to observe criminal suspects or customers (to watch out for theft).

Answer 5

A two way mirror has the reflective material on the outside, compared to a regular mirror. Take a coin and touch it to a regular mirror. You will see a gap between the coin and it's reflection. In a two way mirror, the reflections will touch.

Answer 6

Place your fingernail up against the mirror if there is NO gap between your nail and the nail in the mirror then it's a two way.
One side appears to be a mirror but the other side enables you to see through.
Sorry dont know how it works though, Great question!

Answer 7

The point is so you don't know it's there. Unless you know what a 2 way mirror looks like, you'll never know.
PS - You're hot.

Answer 8

Mirropane