Abstract: The invention pertains to an optical recording medium comprising a homeotropically oriented liquid crystalline polymer film having a T.sub.g between 75-100.degree. C. and a T.sub.c between 110-140.degree. C. and comprising at least one dichroic dye. This homeotropic orientation along with the presence of dichroic dye makes it possible to employ a different technique for writing out and reading data. For, in this case contrast is obtained by the dichroic dye contained in the film being aligned in the same direction as the mesogenic groups of the liquid crystalline polymer. In a virgin film the mesogenic groups, and hence the dichroic dye molecules, are oriented perpendicular to the film's surface, and there is only low absorption of the incident light by these molecules. By local heating or irradiation of the film (e.g., with a laser) the homeotropic orientation is converted to an isotropic one.

Abstract: The present invention is in the field of retardation layers for liquid crystalline displays, more particularly in the field of retardation layers based on super-twisted nematic (STN) liquid crystalline layer. In the retardation layers of the present invention the liquid crystalline polymer is placed between glass substrates wherein at least one substrate has a thickness of 20-500 micrometers. The use of such thin glass substrates reduces the weight and thickness of the retardation layer.The LC polymer film may also be placed between the substrate of the display cell and a thin glass substrate or between the polarizer and a thin glass substrate. In these embodiments of the invention a second thin glass substrate is not necessary and the thickness and weight of the retardation layer is further reduced.

Abstract: The invention relates to a twisted nematic film comprising a non-crosslinked liquid-crystalline polymer having a Tg above 75.degree. C. and a rotational viscosity (.gamma.) of less than 5000 Pascal.seconds (Pa.s) between Tg and Tni. Such twisted nematic films are used in displays. The invention further relates to methods for the preparation of these twisted nematic films, to the use of said twisted nematic films for optical data storage and in writable compact disks and to a display device comprising such a twisted film.