Transparent Mirrors - Two-way and One-way Mirrors
Since the moment they first appeared in history, two-way mirrors managed
quickly to become useful in many types of situations, ranging from
surveillance to solving challenging puzzles that the only mix of
transparent and reflective surfaces could achieve. The first mention of the
two-way mirror discovery goes all the way back to the early 20th century
when the subject of the Emperor of Russia Emil Bloch filed for a patent for
“transparent mirror” in Cincinnati, Ohio, U.S, where he lived at the time.
His design of two-way mirror became the standard for almost all future
models, enabling a thin layer of silver or aluminum to be reflective just
like a regular glass, but also enabling back surface of the mirror to
become transparent when the strong light was flashed toward it.
Essentially, two-way mirrors function like a regular mirror in brightly lit
rooms, but they allow clear viewing from the room that is sufficiently
darkened. Some light from darkened room is penetrating through a mirror
into the bright room, but the users in that room cannot perceive that
because the reflection of the strong light in the mirror overwhelms the
small amount of light that is passing through the mirror.
There are two ways of detecting if some mirror is of two-way variety or
not, but both of those tactics are not 100% accurate all the time. When
putting your fingernail directly on the mirror, you can see if your
reflection starts directly in the mirror surface or behind the thin layer
of glass (small gap between your finger and reflection can be seen). If the
reflection is immediate, then that is the most likely normal mirror. If
reflection has a small gap, there is a chance that is a two-way mirror. The
other tactic involves you cupping your eyes with both hands and closely
examine the surface of a mirror. When most of the light from the room is
eliminated by hands, the small amount of light that is passing through the
window from the darkened room beyond should become visible.
Use case scenarios for two-way mirror are numerous, but most are closely
used for observational purposes. Most notable uses for two-way mirrors are:
– Police use them regularly because this approach allows a lot of
people to observe interrogation without being noticed. This includes
potential witnesses who want their identity kept secret.
– Used so that prisoners who are about to be executed cannot see the
audience in the adjoining room.
Security areas in public areas
– High-risk public spaces such as airports, train stations, and others
can sometimes hide security personnel that is observing the foot
traffic behind the two-way mirrors.
Various experimental research.
Various scientific uses where two-way mirrors are used
as laser “beam splitters”.
– Almost every mirror on reality television sets are two-way mirrors,
with camera personal observing behind them.
Train conductor rooms
– Some newer metro/subway trains hide their train conductor cockpits
behind two-way mirrors.