Abstract: Elongated receiver of continuous structure for seismic prospecting comprising at least one sensitive assembly having two electrically conducting electrodes on both sides of a deformable element subjected to a permanent electric polarization and an electrically insulating compressible element between the deformable element and one of the electrodes. When used for prospecting on the earth the receiver further comprises masses of heavy material secured to one face of the sensitive assembly.

Abstract: A coupling device for coupling a light source, which emits light in accordance with Lambert's law, to a bundle of optical fibers by way of an optical rod. The largest dimension of the source at most equals half the diameter of the core of the coupling rod. The source and the coupling rod are secured in a flexible, elastic support which maintains a distance between a light-emissive surface of the source and the oppositely situated end of the coupling rod. This distance at most equals one third of the diameter of the core of the coupling rod.

Abstract: A family of diphenylic esters are disclosed, which, within certain temperature ranges exhibit mesomorphic phases, either smectic or nematic, having the general formula: ##STR1## where R.sub.1 is C.sub.n H.sub.2n+1 O or C.sub.n H.sub.2n+1 in which n is an integer of from 1 to 10,R.sub.2 is C.sub.m H.sub.2m+1 in which m is an integer of from 1 to 10, andX is Br or CN.

Abstract: A family of organic compounds having at least one mesomorphic phase of nematic type and, in respect of some compounds, one or more smetic phases. The liquid crystals according to the invention satisfy general formula: ##STR1## in which R.sub.1 is an alkyl or alkoxy group having n carbon atoms (n being an integer of 1 to 10) X designates the bromine or the cyano group, Y is a methyl group.

Abstract: Novel mesomorphic substances, constituting, in certain temperature ranges, nematic or smectic liquid crystals which are compounds of the formula: ##STR1## wherein R.sub.1 is an alkoxy group containing 1 to 10 atoms of carbon;R.sub.2 is an alkyl group containing 1 to 10 atoms of carbon;X is Br or CN.

Abstract: Novel mesomorphic substances, constituting, in certain temperature ranges, nematic or smectic liquid crystals which are compounds of the formula: ##STR1## wherein R.sub.1 is an alkyl or alkoxy group containing 1 to 10 atoms of carbon;R.sub.2 is Br, CN or an alkyl (or an alkoxy) group containing 1 to 10 atoms of carbon.

Abstract: A process rendering certain electron masking resins more sensitive or rendering polymers which are unsufficiently sensitive to electrons suitable for industrial utilization, in particular for application to electron masking, a method which employs scanning with a very fine electron beam controlled by the computer. The process involves electron irradiation at low dose levels, sufficient however to create free radicals, followed by diffusion of an appropriate copolymerizing monomer by grafting to the initial polymeric chain opened by the irradiation process. The solubility of the copolymer vis-a-vis certain solvents is selective, enabling the masks to be developed.

Abstract: The present invention relates to data-carrier intended for the high-density recording of information by the use of an etching radiation beam. The data-carrier comprises a substrate upon which there are deposited a very thin film which is absorbent at the wavelength of the etching beam, and a film which is thermodegradable at a temperature lower than the degradation temperature of the absorbent film, the heat developed in the absorbent film being selectively diffused towards the adjacent thermodegradable film.

Abstract: A liquid crystal composition with high negative dielectric anisotropy, which is capable of exhibiting a high dynamic light scattering effect and of inducing similar characteristics into mixtures of the liquid crystal and another nematic liquid crystal and which derives an advantage from a larger mesomorphic temperature range, which comprises at least one compound of the formula: ##STR1## wherein R represents NO.sub.2, bromine or cyano; R.sub.1 is an alkyl or alkoxy group and R.sub.2 is an alkyl group.

Abstract: The permanent electric polarization is imparted to the sensitive element by electronic bombardment within an enclosure wherein prevails a rarefied atmosphere and in which said bombardment is followed with a coating of the so-polarized sensitive element with a film of liquid of very low saturated vapor pressure whose dielectric strength is higher than that of the rarefied air of the enclosure and having advantageously lubricating properties.

Abstract: A method of manufacturing a metallic die intended for the duplication of a video frequency signal recording. A master impression is engraved in a positive photosensitive resin layer having a thickness on the order of 3000 to 4000 A and covering a metallic substrate, by exposing the layer to a laser beam modulated by the signal which is to be recorded and removing the exposed portions of the layer to bare the underlying substrate. A metal layer substantially equal to the thickness of the initial photosensitive layer is deposited on the non-exposed photosensitive layer and the bared portions of the substrate. Thereafter, the non-exposed photosensitive material and overlying portions of the metal layer are eliminated by a solvent for the non-exposed photosensitive material to form the metal projections of the die.

Abstract: A dielectric thin layer consisting of polymerized perfluoro-2-butene:(C F.sub.3 -C F=C F-C F.sub.3).sub.npresenting very good characteristics for production of single or multi-layer capacitors, obtained with a rapid deposition by glow discharge in an a.c. electrical field. The glow discharge is carried out in the gaseous phase of perfluoro-2-butene under highly reduced pressure and an a.c. voltage of 300 volts, the maximum rate of layer formation (0.7 micron per minute) being obtained for a frequency of 13.56Mc/s, at a temperature of 0.degree. C. under a pressure of 0.1 Torr when the useful power of the glow discharge is of 5 to 10 watts.

Abstract: Novel mesomorphic substances, constituting, in certain temperature ranges, nematic or smectic liquid crystals, are compounds of the formula ##STR1## wherein Y is H or CN;R is alkyl or alkoxy of 1 to 10 carbon atoms;R' is alkyl of 1 to 10 carbon atoms or ##STR2## and X is Br, Cl or CN.

Abstract: The present invention relates to a family of substances which, in different temperature ranges, exhibit smectic or nematic properties of mesomorphism. Their general formula is: ##STR1## where R designates one of the three radicals:C.sub.n H.sub.2n + 1 ; ##STR2## (n being a whole number ranging from 1 to 20) and X designatating a halogen (Br preferably) or the nitrile radical C N.

Abstract: An organic compound having a high negative dielectric anisotropy is capable, by mixing with a nematic liquid crystal, of improving the dynamic scattering effect of the liquid crystal. The organic compounds have the formula: ##STR1## in which R is either a fluoro or a nitrile radical and wherein R.sub.1 and R.sub.2 are alkyl radicals. An excellent dynamic scattering effect is obtained by mixing the new organic compound even in a low proportion with a nematic liquid crystal.

Abstract: A method of manufacturing an electron-sensitive resin capable of constituting the material of an optical waveguide having a width of the order of 1 micron and transmission loss lower than 2 db/cm, is provided. The method comprises, carried out under conditions of extremely high purity, the hydrolysis of trichlorosilane, to give phenylsilanetriol, the preparation of a benzenic collodion of this product and then the polymerization in the hot state of a phenylsilanetriol solution, and the conversion of the resultant polymer into the polyphenylsiloxanol which is fractionated by successive extremely fine filtering operations carried out upon a solution of this product, into batches having different degrees of polymerization, each of them fitting a typical optical waveguide.

Abstract: A nematic liquid crystal for display devices, capable of presenting a helical structure in a wide temperature range down to -10.degree. C, is provided. This is a mixture of substances taken from two groups of the formulae: ##STR1## wherein n is an integer from 1 to 12.

Abstract: A high precision silica coating, is provided. A thin film of a resin, from the polysiloxane group, for instance polyvinylsiloxane, is irradiated by 10,000 electron-volts. The resin converts in an insoluble product in the areas exposed according a predetermined pattern. After a heat treatment in oxidizing atmosphere, the remainder of the film is eliminated.

Abstract: An electron sensitive resin comprising a random polymer of ethylene glycol methacrylate with triethylene glycol dimethacrylate, randomly crosslinked, and having a degree of polymerization of from 10 to 1000, is described.

Abstract: The present invention relates to the protecting against scratching and fouling of a data carrier which carries a relief impression readable optically by transmission. The data carrier in accordance with the invention is protected by a transparent protective layer with substantially smooth faces, which adheres to the peaks in the relief of the impression in such a way as to prevent the troughs in said relief from being filled up.