What is a two-way mirror?
Perhaps you’ve received the e-mail. “Department stores use two-way mirrors in their dressing rooms, so watch out!” More likely, you’ve seen a television show in which one detective interrogates a suspect in a room with a mirror, while another detective watches from another room in which that same mirror acts a window. Both scenes describe a two-way mirror—a piece of glass that acts as a mirror if you look at it from one side and a window if you look at it from the other. You either see your reflection, or you see right through it. The possible surveillance applications are infinite; you can watch someone without their knowing it. Transparent mirrors, one-way glass, observation mirrors—they are all just different names for the same product. It is especially confusing when these two-way mirrors are called one-way mirrors. True one-way mirrors, however, are actually regular mirrors; the light is only reflected “one way.” With a two-way mirror, on the other hand, light is both reflected an
