Mirrors

Two kinds of mirrors are used for security purposes. The most obvious is the large, round, convex mirror that may be mounted in the corners of the store.Their lens shape gives them a wide angle of vision, but at the expense of image size. Like the message on your car's right outside mirror says, 'Objects may appear closer than they appear.' In other words, you may be visible in the convex mirror, but you'll look so tiny it's impossible to make out what you're doing.This type of mirror has another weakness. Simply put, if they can see you, you can see them. That';s the nature of mirrors. If you glance into a mirror and find yourself looking directly into someone's eyes, you can be sure he is watching you.The other type of mirror is the two-way, or front-silvered, mirror. When you look at the mirror, you see a reflection. But if someone is behind a two-way mirror, he sees you, not his own reflection.Normal mirrors are sheets of glass silvered on the back. Actually, nobody uses silver anymore; the back of the mirror is more likely coated with aluminum or steel). The two-way mirrors are lightly silvered on the front surface. The silvering is light enough to be reasonable transparent, provided the light in back is kept low. To put it more simply, regular mirrors are silvered on the back side, security mirrors on the front. Therefore, with a regular mirror, you're looking through a sheet of glass at the reflected image. With a security mirror, the image is right there on the front.There's a easy way to tell the difference. Take a nail file, sharpened pencil, pen, or the other hand, sharpedged item and touch the surface of the mirror. If you're using, say, a pencil there should be a noticeable gap between the point of the pencil and the point of the reflected pencil's image. Typically, the gap will be between and eight and a quarter of an inch.If the pencil tip rests directly against the reflected image of the pencil's tip, you're probably being watched. In a two-way mirror store, a person must assume that they're always under observation from that mirror." This is what supermarket security guard Andrew said.