E.i. Dupont De Nemours and Company

Steven William Macmaster

Eric William Teather

Eric W Teather

A reflection-type projection screen is provided having uniformly high gain over a wide range of viewing angles. The projection screen includes a dual-purpose light reflective, supportive substrate including at least one unpigmented flash-spun plexifilamentary film-fibril sheet having a light reflectance of greater than about 85% and a gloss of less than about 10% when measured at a 60&#xb0; incident angle, and an optical diffusion layer of a light transmissive melt-processible polymer containing diffusion-enhancing particles covering at least one surface of the substrate. The projection screen has an optical gain of between about 0.90 and about 2.0 and the optical gain deviates by no more than about 8% over viewing angles between &#x2212;60&#xb0; and +60&#xb0;. The projection screen has good drapeability, rollability the ability to lay and hang flat. The projection screen can also be recycled.

Reflection-type projection screen

A security hologram is disclosed that is invisible to a human eye or to various optical detectors until the hologram is optically coupled to a suitable modifier (e.g., a prism). Also disclosed is a method of recording the security hologram and a method of using the hologram in security applications to establish authenticity of article(s).

Security hologram, method of recording same, and method of using same wherein the holographic imaging includes a single coherent beam of electromagnetic radiation in combination with a Lloyd's mirror to provide both reference and object beams

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Springfield, PA, United States of America

Steven William Macmaster