Abstract: This patterning system has the ability to uniformly image a mask onto a substrate having nonlinear exposure characteristics, has large-area exposure capability, and comprises: (a) a stage system capable of synchronously scanning a mask and a substrate in one dimension, and when not scanning in that dimension, capable of moving them laterally in a direction perpendicular to the scan direction so as to position the mask and substrate for another scan partially overlapping the preceding scan, thus exposing the full substrate in an overlapping scan-and-repeat fashion; (b) an illumination system capable of illuminating on the mask a region of a predetermined multisided shape which has at least one of its sides curved, the curvatures of said curved sides being so determined that adjacent scanning exposures are compensated in their overlap regions for the nonlinear response characteristics of the substrate so as to provide uniform cumulative response; (c) a projection assembly capable of imaging the illuminated regi

Abstract: The invention is a document security system characterized by a data substrate having photographic or printed information on a base print, and also having a personalized polarization-altering overlay sealed to the base print and encoded with additional coded information readable under the influence of a polarizing viewer. The low-security information, such as name, social security, account number and photograph, are printed on a card to form the base print. Additional information of greater security, which may be a bar code or alphanumeric characters, is imprinted in the polarization-altering overlay by an appropriate physical process, such as radiation exposure or thermal, chemical or mechanical treatment, which optically modifies localized regions of the overlay.