Hand held laser scanners are the most expensive of the scanning devices, but offer the largest depth of field making them an appropriate choice for a wide variety of non-contact applications. Hand held laser scanners use a laser diode to create a scan line by projecting a beam of energy off a rotating prism or oscillating mirror. The beam is reflected out the scanner window onto the bar code, where light energy from the bars and spaces is reflected back to the scanner, collected on a mirror, focused, and read by a photo detector. The resulting signal may then be read using decoding software within the scanner or at the terminal.

Hand held or fixed mount input devices are held in the hand. Others are fixed in stationary positions, usually near a conveyer belt of some sort. Grocery store check-out registers use a type of fixed mount scanner called a plate scanner.

Code 128 symbology is a very compact bar code for all alphanumeric applications. The full 128-character ASCII character set can be encoded in this symbology. If you have your choice, Code 128 is generally the best all-around choice you can use.

t-generation moving beam laser installations was a Helium-Neon laser tube. In the past few years semiconductors capable of producing laser light have been incorporated in most laser products. Laser diodes, both visible and infrared, are in a package about the size of an LED. Compared to the gas tube used to create Helium- Neon lasers, the laser diode is much smaller, requires significantly less power, and is more durable. This makes these hand-held devices suitable for portable data collection terminals or for fixed-station decoders that are powered from the terminal.

UPCs originated with a company called the Uniform Code Council (UCC). A manufacturer applies to the UCC for permission to enter the UPC system. The manufacturer pays an annual fee for the privilege. In return, the UCC issues the manufacturer a six-digit manufacturer identification number and provides guidelines on how to use it. You can see the manufacturer identification number in any standard 12-digit UPC code, the UPC symbol printed on a package has two parts, the machine readable bar code and the human readable 12-digit UPC

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