A bar-code optical scanner in which a converging prism is disposed in front of the light source to concentrate emitted light into a light beam, permitting it to be projected onto the bar code; the lens which is disposed between the reflector and the photosensor has a rectangular ...http://www.google.co.uk/patents/US5734157?utm_source=gb-gplus-sharePatent US5734157 - Bar-code optical scanner
