Optical reader and use

Abstract

An optical reader is provided for reading a symbol representing information having areas of different light reflectivity. The optical reader comprises a radiant energy source, a photodetector, an optical system and a decoder. The radiant energy source generates a radiant energy for illuminating a target region. The photodetector generates output electrical signals indicative of the radiant energy incident thereon. The optical system includes a projection portion and a collection portion. The projection portion directs the radiant energy along a projection path extending from the radiant energy source to the target region. The collection portion collects the radiant energy reflected from a symbol when the symbol occupies the target region and directs the collected radiant energy along a collection path extending from the target region to the photodetector. The collection portion includes one pinhole aperture disposed upstream on the collection path from the photodetector without intervening refraction or diffraction and one magnifying lens disposed upstream on the collection path from the pinhole aperture without intervening refraction or diffraction. The decoder decodes the output electrical signals of the photodetector to provide indication of the information contained in the symbol.