Reduction and Enlargement using Unity Magnification Gradient-Index Lens Arrays

Arrays of gradient-index lenses are commercially available as Selfoc® lens arrays from the Nippon Sheet Glass Co. The lenses are radial gradient cylinders that are arrayed in a parallel fashion, and thus are necessarily confined to unity magnification (1×) imaging. A primary application of Selfoc lens arrays has been in personal and engineering drawing photocopiers copiers that operate at only unity magnification. For other light-lens photocopiers, in addition to unity magnification, reduction and enlargement copying has become a universal customer requirement that is now generally considered a standard feature. In an attempt to broaden the applicability of Selfoc lens to more general office copying needs, a reduction/enlargement gradient-index lens array has been developed and previously described in Ref. 1. This R/E Selfoc has certain short comings; only one value of reduction and its reciprocal for enlargement are possible, and it is limited to relatively small field sizes (original/copy) such as B4/A4 paper combinations with magnifications in the range of 70-140%. Finally, image quality varies across the field, being lower at the edges than at the center.