Jean-Claude Lehureau

P‐120: Volume Holographic Technology for the Viewing Angle Compensation of TN‐LCDs

Thanks to holographic technology, the hybrid holographic compensators offer interesting properties for the versatility of the compensation design as well as for product integration. The adaptability of the hybrid holographic compensator is demonstrated through the implementation of the compensator on two avionic displays.

Subwavelength volume holographic grating in photopolymer for the liquid crystal display viewing angle compensation

With today’s organic photopolymer materials allowing high resolution, it is possible to record subwavelength volume holographic index gratings, i.e. index gratings with a period much smaller than the wavelength operating in the form birefringence regime. Such components are of interest for the direct view liquid crystal displays that suffer from a narrow viewing angle. In fact, by providing high birefringence, they compensate the intrinsic birefringence of the liquid crystal and thus, improve the viewing angle properties of the liquid crystal displays. Recently, we introduced a hybrid holographic compensator combining an “in plane” commercially available birefringent film and a slanted optical-axis subwavelength volume index grating recorded in a DuPont photopolymer. In this paper, we present the hybrid holographic compensation and its interesting features for TN-LCD viewing angle improvement. More particularly, a hybrid holographic compensator is designed for avionics application. It is based on a 120nm-period volume index gratings achieving an index modulation of 0.045 with a 33°-slant angle of the optical axis. The hybrid holographic compensator was manufactured and implemented on an avionics equipment from Thales Avionics. Visual inspection as well as contrast measurements showed a good improvement of the viewing angle characteristics.

High-data-rate, high-density magnetic tape recorder using matrix writing head and Kerr reading head

The following new components have been developed for magnetic tape recording: the matrix writing head, which allows fine track pitch and high integration (1,024 tracks) at reasonable cost, and the Kerr reading head, which takes advantage of optics for high sensitivity, parallelism, and easy tracking. The feasibility of reaching a data rate in the range of 40 megabytes per second and a density of up to 2500 tracks per inch (TPI), 50 kilo flux changes per inch (KFCI) on half-inch tape has been demonstrated.<<ETX>>