Abstract: A security material for documents comprises a first layer of material, such as a polymeric film or laminate, having first and second sides. A pearlescent material is applied to at least one of the first and second sides. The pearlescent material defines a pattern comprising at least two different colors that are at least partially interlocked in the pattern, and the pattern permits printed information that is overlaid by the pattern to be effectively perceived.

Abstract: A remote emissions sensing system and method for sensing exhaust emissions from motor vehicles is provided where the system determines the opacity of an exhaust plume. The system comprises a radiation source that emits radiation which is passed through the exhaust plume of a motor vehicle to one or more detectors arranged to receive the radiation. Multiple wavelength opacity measuring embodiments and monochromatic wavelength opacity measuring embodiments are disclosed.

Abstract: An optical disc for storage and retrieval of digital data, and a system and method for protecting the optical disc is disclosed. The optical disc has projections or embossments on one or both surfaces. When the optical disc is placed on a substantially flat surface such as a tabletop or a desktop, the projections act as pedestals that elevate the optical disc above the flat surface. The resulting gap or clearance helps prevent damage to the optical disc caused by contaminants on the flat surface or by defects in the flat surface. The projections are sized to provide adequate clearance between the disc and the flat surface, while minimizing interference between the projections and components of optical disc readers and drives. The optical disc may also include one or more depressions that are sized and configured to receive projections from another disc, which facilitates stacking of the optical discs.