[GH85Carrera]

"On 26 June 1974, the first installation of supermarket scanners entered service in a Marsh supermarket in Troy, Ohio. This Spectra Physics model A price scanner, is one of those first ten scanners. A package of Wrigley's chewing gum became the first purchase made with scanners that could read the new Uniform Product Code (UPC or barcode). Mounted within the unit a helium-neon laser projected a beam onto a rotating mirror and thence up through a glass plate on the top surface. The light reflected from the code label on the package and was detected by a photo-diode. A computerized cash register matched the signal from the photo-diode with information in a stored database to determine which product was being scanned."