Working Knowledge: Quick Scan; May 2001; Scientific American Magazine; by Mark Fischetti; 2 Page(s)

Look around your home tonight, and you may be surprised at how many items sport bar codes: groceries, magazines, mail, books, furniture, printed circuit boards inside computers, perhaps even your driver's license. Several types of bar-code readers make instant sense of these high-tech graffiti. Penlike wands are dragged across the bars of a code. Laser scanners are aimed like a gun. Charge-coupled-device (CCD) readers are held up against it. The devices illuminate codes with 645-to 690-nanometer (red) light and convert a code's image into a voltage waveform, which a decoder translates into numbers and letters for a computer or terminal. Companies such as Intermec Technologies, Metrologic and PSC sell $2 billion worth of readers every year.

Wands, common in libraries and hospitals, are the least expensive and most durable readers. They can be frustrating, however, because the operator must hold the wand against a bar code at a certain angle and move it back and forth at a consistent speed. Laser scanners such as those in grocery stores are the most widely used, although they are also the most expensive at $300 to $1,100 apiece. A typical laser can read a code from four to 16 inches away, and longrange warehouse models can reach up to 30 feet.