A supermarket scanner reads the Universal Product Code (UPC) bar code symbol appearing on grocery items. The scanner uses the red light from a Helium-Neon laser and some means to deflect or scan the laser beam across the symbol as it passes across a window or aperture in the top surface of the scanner. A detector within the scanner senses the variations in reflected laser light as the laser beam scans across the symbol. These variations are converted to an electrical signal which is decoded to identify the product.
Become a member or log in to view the full text of this article.
OSA Members get the full text of Optics & Photonics News, plus a variety of other member benefits.