Objective The main results and conclusions of the project can be summarized as follows. Polyesters with 6 or 8 methylene groups in the flexible spacer, a cyano-substituted azobenzene as the photoactive chromophore in the side chain, 12 methylene groups in the acidic part of the main chain, with a molar mass between 20,000 and 70,000 are eminently suited for optical storage. These films are mechanically robust; free standing films of these polyesters can be stretched 1000% before breaking. A grating recorded in 1992 in a film of P6a12 with its undiminished diffraction efficiency testifies to the potential for optical storage in these polyesters. In addition, holograms of two-dimensional transparencies as well as three-dimensional objects have been recorded. A compact and portable polarization holographic storage of an A4 size has been designed. The experimental observations can be summarized as follows: Initially, the polyester films are semi-crystalline or in a poorly ordered mesophase. Optical anisotropy can be induced at room temperature, with a polarized laser beam. This influences only the photoresponsive azobenzenes. The anisotropy is due to local variations of the material refractive index. It has been shown that the mesogens are aligned perpendicular to the polarization of the laser. In fact, also the segments of the main chain and the side chain are aligned perpendicular to the polarization of the laser beam. No anisotropy can be induced above 40 C. Heating the films to a temperature corresponding to the melting of an aggregated phase which might involve both the main and the side chains, is necessary in order to randomly orient the azobenzenes and as a result destroy the anisotropy in the material. This temperature is typically well above the glass transition temperature. The information stored is completely stable otherwise. The following mechanism is suggested for optical storage in the polyester: The film obtained by casting is macroscopically isotropic and consists of lamellar microdomains where an organized structure of side groups prevails; the polarized laser beam melts these lamellar domains either through direct heating due to absorption or deposition of heat through trans-cis-trans isomerization cycles and causes the reorientation of the azobenzene moieties and main-chain segments. After switching off the laser, the lamellar domains start to reform domains whose orientation progressively approaches that of the perpendicular to the polarization direction of the incident beam. As they stand, the polyester films are ripe for storage in systems. Such systems have powerful archival capacity - such as for medical documents, x-ray pictures, for satellite images and the like.In this project,side-chain liquid crystalline(SCLC) polyester materials and devices for parallel optical processing will be developed.Specifically,the proposed research is directed towards the development of an erasable holographic memory providing a high storage capacity on the order of 10-100Mbits/cm{2}. The major research tasks are:1. fabrication and characterization of liquid crystalline polyesters containing the cyanobenzene group in the side-chain.2. optical information storage applications of side-chain liquid crystalline polyester films,such as high resolution computer generated holograms.3. design of new functional side-chain liquid crystalline polyesters with the aim to achieve a recording energy of 10 to 100 mJ/cm{2}.4. design of optical processing systems,e.g. spatial light modulators and joint transform correlators,incorporating side-chain liquid crystalline polyesters.The materials and components developed under this project could be used in state-of-the-art apparatus performing analog optical processing such as vision systems and in digital devices,for example,optical digital memories. Fields of science engineering and technologymechanical engineeringvehicle engineeringaerospace engineeringsatellite technologyengineering and technologymaterials engineeringnatural sciencescomputer and information sciencesdata sciencedata processingnatural sciencesphysical sciencesopticslaser physics Programme(s) FP3-BRITE/EURAM 2 - Specific programme (EEC) of research and technological development in the field of industrial and materials technologies, 1990-1994 Topic(s) 1.4.4 - Optical materials Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator RISO NATIONAL LABORATORY EU contribution No data Address (POBOX 49) 4000 ROSKILDE Denmark See on map Total cost No data Participants (3) Sort alphabetically Sort by EU Contribution Expand all Collapse all Consiglio Nazionale delle Ricerche (CNR) Italy EU contribution No data Address FAC.ING./VIA DIOTISALVI, 2 56100 PISA See on map Total cost No data UNIVERSITY OF ESSEN Germany EU contribution No data Address Universitatsstrasse 5-7 45117 ESSEN See on map Total cost No data Università degli Studi di Pisa Italy EU contribution No data Address Via Diotisalvi 2 56126 Pisa See on map Total cost No data
