Two-way mirrors

Two-way mirrors, also referred to as one-way mirrors, are primarily used by police to observe criminal suspects or by retail employees to monitor customers for theft. Although two-way mirrors are famous for their placement in police interrogation rooms and shopping malls, they have become more readily available to the public and are increasingly used in businesses and even private homes. With the public’s increasing access to technology, two-way mirrors have become available to anyone who is interested. Websites advertise the advantages of two-way mirrors on personal property as ways to keep an eye on babysitters and others doing work inside one’s home. On the other hand, some voice concern at the availability of two-way mirrors since owners can place them inside dressing rooms, rental property, or hotel rooms to facilitate voyeurism. The harmful possibilities of two-way mirrors have increased the public outcry for privacy laws that would protect those who are unknowingly watched.
Two-way mirrors are an effective means of surveillance since those being watched are usually unaware of it. This is because of the way two-way mirrors are designed. Two-way mirrors are commonly misunderstood to be a mirror from one side and a window (letting light through) from the other side. Actually, the two-way mirror is only semitransparent because it is letting about half of the light through, and reflecting the other half of the light, from both sides. This effect occurs when one side is in the dark. When no light goes through from the dark side to the bright side, and almost no light is reflected back from the bright side to the dark side, it acts as a sort of window. Therefore, those on the dimly lit side can see through the mirror, while those on the brightly lit side see their own reflection.
Because of the properties of two-way mirrors, they are commonly used in police interrogation rooms. This allows law enforcement officials to observe the interrogation and questioning process and to monitor for misconduct by both the criminal suspect and those doing the interrogating. In addition to being used in interrogation rooms, two-way mirrors have been used to monitor activity within shopping malls, banks, post offices, and private businesses. Since two-way mirrors are semitrans-parent, surveillance cameras can be placed behind them to capture any activity within its viewing range. This is probably the second most popular use of two-way mirrors. With a camera placed behind the two-way mirror, employers can monitor not only customers, but their own employees as well. The placement of cameras behind two-way mirrors is an effective means of identifying and apprehending those breaking the law.