Nitto Denko Group CSR & Annual Report 2011
ResearchandDevelopmentCSR & Annual Report 201124MoleculeSkullFurther Improvement of New Organic Polymer-type Hologram Display and Renewed Publication in NatureUsing our novel organic photorefractive material, which has the world’s highest level of diffraction efficiency and a high writing speed, US-based Nitto Denko Technical Corporation (NDT) has succeeded in developing an improved rewritable hologram display with outstanding image persistency. The project was carried out in collaboration with a research group led by Professor Nasser Peyghambarian of the University of Arizona. In February 2008, detailed presentations of the related system, methods, and other aspects were published in several scientific journals including Nature – one of the world’s leading scientific journals – along with various news media including CNN. Following further progress and improvements, another paper was published in the November 2010 issue of Nature, attracting further interest. 1. Features of the Technology(1) Refreshable three-dimensional moving images through improved rewritabilityThe new type of hologram is a three-dimensional image recorded on a film or other medium in three-dimensional form. Holograms are already in use on credit cards, bank notes, etc. to prevent counterfeiting. When viewed from different angles, the image pattern undergoes subtle changes enabling the human eye to perceive it as a three-dimensional image (Figure 1). Compared to other three-dimensional image display methods, the hologram gives a more natural effect and is less fatiguing on the human eye.However, conventional hologram recording materials were not rewritable and were therefore unable to reproduce continuous moving images. NDT therefore worked on the development of an organic polymer system which could be manufactured at low cost and coated easily onto a glass plate or plastic substrate. Then, in collaboration with the University of Arizona, NDT focused on the photorefractive method and succeeded in making the image refreshable by enhancing the material and optimizing fabrication. Since 2008, the refreshing speed in particular has been drastically increased; for instance, what used to take three minutes on a 6-inch by 6-inch display can now be rewritten in a matter of seconds. Further studies are now in progress aiming to improve speed by more than a factor of ten to match the video rate. (2) Enabling color hologramsThe previous photorefractive method showed red images only. However, the present project succeeded in realizing full color by developing new material chemical components and introducing special device structures.(3) The world’s largest display sizeThe display size as of 2008 was limited to 6” x 4”. By utilizing our technological strength and polymer processing technology know-how, the Nitto Denko Group has successfully developed a flawless, large-sized three-dimensional holographic display with good uniformity. The display size of 12” x 12” (Figure 3), an enlargement of nearly ten times, is the world’s biggest rewritable 3D photopolymer material-based sample to date. The Nitto Denko Group is pursuing R&D efforts to achieve a further tenfold increase in speed with the aim of equaling video refreshing speed.(4) Enables three-dimensional images not only in the horizontal but also the vertical planeAlmost all existing three-dimensional display devices, such as three-dimensional televisions, employ a display method wherein two slightly different versions of an image are separately projected in a stripe pattern for the left and right human eyes. Human eyes Figure 3: Size of newly developed display medium (yellow section)Red rosesFigure 2: Color images. Various colors can now be displayed.Blue rosesTraffic lightFigure 1: Rewritable hologram image created using the newly developed system. By combining images viewed from different angles, the image is made to appear as 3D.