Abstract: Image-bearing elements made of support material that transmits light longitudinally through its cross-section, in a plane parallel to its image-bearing surface, are disclosed for use in an information retrieval system. The retrieval code used in identifying each element is generated by modulating a directed beam of light transmitted longitudinally through the element's cross-section. Modulation of the directed beam is accomplished by, for example, placing opaque spots on a cross-sectional area of the element, punching holes in the element, or by placing a code mask at the end of the element from which the directed beam emanates. The code modulated beam is photoelectrically detected and the resulting electrical retrieval codes are used in the retrieval process.