Liquid crystal cell using the electrically controlled birefringence effect and processes for the production of the cell and a uniaxial medium or material of negative optical anistropy usable therein.
Liquid crystal cell having a homeotropic structure, with compensated birefringence for said structure.
Active matrix screen for the color display of television images or pictures, control system and process for the production of the screen.
Cell with a double liquid crystal layer using the electrically controlled birefringence effect and process for producing a negative optical anisotropy uniaxial material usable in said cell.
Illuminating device for a large screen making it possible to uniformly illuminate said screen by means of a light arriving at a low angle of incidence .theta., wherein it comprises n.p light sources and n.p optical focusing elements in matrix form, as well as means for ensuring that the light beams ...
The invention relates to a method of controlling an optical characteristic of a material and it is concerned also with devices and image-forming means for carrying out the method.
A device for determining the contrast of a display screen as a function of the observation direction. This device comprises a first convergent objective (12) for forming the image (19) of the Fourier transform of an elementary surface (9) of a screen (6) in the image focal plane (Fi) of the first ob ...