Abstract: A grating structure by high dispersion volume holography that applies, for example, to pulse compression or stretching devices. The grating structure includes a transmission volume holographic grating produced on a reflective support. The grating includes strata inclined to the plane of the support, the angle of inclination of the strata defined with respect to the normal to the support and the pitch of the strata being chosen such that a light beam of a predetermined mean wavelength, incident on the structure with a predetermined angle of incidence, undergoes a first passage through the grating, is reflected by the reflective support, undergoes a second passage through the grating, and is only diffracted by the grating during one of the first and second passages.

Abstract: A display device with a liquid crystal cell including a layer of twisted nematic liquid crystal placed between two polarizers and including, between the liquid crystal layer and each of the polarizers, a structure for compensating for cell contrast variations according to the observation angle which has an orientation in the plane of the cell. The pass directions of the polarizers are separated by an angle of 90+A degrees, in which A is not zero, and the orientations of the two compensation structures are separated by an angle of 90+B degrees, in which B is not zero. Such a structure may find particular application to a liquid crystal screen, especially for avionics.

Abstract: The invention concerns a grating structure by high dispersion volume holography and applies, for example, to pulse compression or stretching devices.