Abstract: A photodetector and light source assembly useful in a bar-code reading system comprises a semiconductor substrate with holes therein. A light source form of LED's mounted on one side of the substrate corresponding with the respective holes illuminates an object plane, via a lens system, on the other side of the substrate. Preferably, the light received by the photodetector is slightly out of focus. Advantages include a saving in cost and size together with an improved depth of field and efficiency of illumination.