Abstract: Method for obtaining an organic polycrystalline material having in particular electro-optical properties, said material obtained and an electro-optical modulator comprising said material. This method includes a stage (1) for preparing a powder having a size grading of 500 to 800 nm of an organic compound having a delocalized system of .pi. electrons and presenting a non-centrosymmetrical crystalline structure, as well as intramolecular load transfer groupings, a stage (2) for drying the powder under vacuum, a stage (3) for pre-pressing the powder under vacuum, and a hot stage (5) for the uniaxial compression of the dried powder under vacuum. This method enables polycrystalline materials to be obtained, said materials comprising elongated monocrystalline grains orientated according to a given direction.

Abstract: Method and device for the optical filtering and photodetection of intensity-modulated optical signals.Signals are injected into at least one resonating type semiconductor laser amplifier (2) close to the active layer (14) of this amplifier, the latter being polarized below its threshold current and having at least one resonance wavelength adjusted so as to coincide with the wavelength of at least one of the optical signals in order for this optical signal to be amplified by the amplifier, and the voltage existing between the terminals of the amplifier is detected so as to obtain, in the form of an electric signal, the information carried by the amplified optical signal when the angle between the polarization direction of the latter and the direction of the active layer is small.Application for the embodiment of optical receivers.

Abstract: Giant liquid crystal display means. The means comprises projection modules (MP) associated with mirrors (M1, M2) and a large screen (E). The screen carries colored filters (R, G, B) and the liquid crystal displays are monochromatic. Application to the projection of large television or pictures.

Abstract: The invention relates to a quantization process in an encoding by transformation for transmission on a low rate link of an image signal, said image signal being processed in the form of blocks, each containing a set of digital data, each block being transformed to produce a transformed block of coefficients (Ci) representing the frequency components of the block, each transformed coefficients of a block being quantified during a scan by comparison with quantization levels, the first being called the threshold, the process being characterized in that the quantization is performed with a threshold (T) able to vary between one transfored coefficient (Ci) and the next (Ci+1) in the scan, depending on whether the transformed coefficient does or does not fulfil the conditions -T<Ci<+T.

Abstract: The multiplier according to the invention comprises N shift registers (RD.sub.O, . . . , RD.sub.N-1) containing the words x.sub.i on B bits, N conditional adders (AdC.sub.O, . . . , AdC.sub.N-1) each adding to the partial sum which they receive a constant coefficient (a.sub.1), conditional on the value of the bit (x.sub.i,j) which they receive from the associated register (RD.sub.1) and an adder accumulator (AdAc). The digital filter using such a multiplier also comprises a parallel word input register.

Abstract: According to the invention, the control messages are constituted by a general addressing message (GCM), followed by shared addressing messages (SACM). The message (GCM) contains all the information common to all the user groups and a confirmation data item of the group of users and the messages (SACM) a shared address. Thus, the group is defined in a manner inherent in the control messages and can undergo reconfiguration at any time.Application to more particularly satellite broadcasting of television programmes.

Abstract: It realizes the chemical vapour phase deposition method using a plasma maintained by surface waves in a tube (2) for obtaining a preform and comprises photodetection means (50) sensitive to the light emitted by the deposition area (54) of the vitreous coating resulting from the reaction between appropriate gaseous compounds and able to supply information relative to the emission area of said light, and means (52) for controlling the displacement of the deposition area, displacement being such that the thickness of the coating is uniform in the tube, and control means controlling the power of the microwave generator (30) of the apparatus as a function of the information. Application to the field of telecommunications.

Abstract: A recursive type adder for calculating the sum of two operands. It is used to calculate the sum of two binary data numbers using adders in the form of integrated circuits, particularly for information processing systems wherein the adders constitute one of the fundamental operations of data processing. The invention is classified in the category of parallel-parallel type adders.