Michiharu Yamamoto, W. Lin, T. Gu, D. Flores, P.Wang, Savas Tay, P.-A. Blanche, R. Voorakaranam, R. A. Norwood, & N. Peyghambarian
Nitto Denko Technical Corporation, 501 Via Del Monte, Oceanside, CA, 92058, USA Univ. of Arizona, Optical Science Center, 1630 East University Blvd., Tucson, AZ, 85721, USA
The hologram approach can hold 3-D images recorded on mediums and are used in applications such as “counterfeit-proofing” of credit cards and banknotes. Conventional holographic recording materials, such as gelatin and silver halide, are non-rewriteable. Therefore, once the holograms have been recorded, they are not allowed to overwrite or rewrite continuous dynamic images on the same mediums. Photorefractive material and approach are superior by virtue of not only their rewritable characteristics but also the diffraction efficiency at high level as well as the excellent writing speed. However, not many materials and systems are not available and known for practical applications, so far. Unlike previous photorefractive materials, we developed new type of photorefractive material, in which images once recorded could be retained for a long time, while maintaining the high image brightness and fast writing speed. Since the image persistency can be retained up to several hours, the recorded images can now be adequately viewed over a long period. Since the image can form patterns which are subtly different by viewing from different angles, human eyes would perceive the patterns in total as three-dimensional images. The size of the hologram display is larger than the previously reported size, at 15 cm x 15 cm, which is the largest reported for a photorefractive material-based sample with good homogeneously and defect-free. We are currently working on larger size display fabrication and envision A4 size devices within a year. We hope to achieve color holograms by angular multiplexing of several holograms that can be readout by different color reading sources. Foreseeing various holographic applications for the photorefractive material developed this time, we plans to actively promote the development of various devices going forward for 3D visualization application areas such as medical imaging, industrial CAD-CAM design, and security devices. Keywords:Organic photorefractive material, Updatable, Large area,
