Abstract: The core (2) of a monomode fiber is surrounded by a slightly monomode annular waveguide (6) guiding masking light having the same wavelength as the light conveyed by the core. The invention is particularly suitable for telecommunications.

Abstract: An erbium-doped fiber laser amplifier (1), characterized by the fact that said fiber (3) is doped to a concentration lying in the range 5 ppm to 50 ppm, that the length of said fiber lies in the range 250 m to 30 m depending on the selected concentration of doping, and that the radial position of the doped zone substantially coincides with the energy maximum of the set of propagation modes in said fiber at the pumping wavelength.

Abstract: A mist is formed by an ultrasonic generator (5) from a liquid solution containing a dopant, and the mist is inserted into the tube blank to be doped (4) by means of a flexible pipe (2) in order to deposit microdrops on the inside surface of said tube blank. The flexible pipe is withdrawn progressively so that deposition takes place along the entire length of the tube blank. The deposit is dried and a new layer of glass is deposited thereon. The dopant from the deposit is heat diffused into the glass of the tube blank and of the new layer of glass. The invention is particularly applicable to fabricaitng rare-earth-doped silica preforms for the purpose of drawing optical fibers that can be used to constitute lasers or sensors.

Abstract: A laser diode (4) emits a beam which is reflected by a plane mirror (12) and by a spherical focusing mirror (2) in order to form a beam (40) which is focused on a read window which is a segment of a read line (6). Said line extends transversely relative to a film (16) running over a drum (20) which rotates about an axis (22). The window occupies the width of the soundtrack on the film. The light passing through said soundtrack is received by a photo cell (34) which provides the sound signal. The invention is particularly applicable to sound motion pictures.

Abstract: The method is intended to provide cables (10) having an optical fiber (1) and suitable for mechanically severe environments, while remaining small in section. Heretofore, the mechanical strength of optical fiber cables has been obtained by plastic structures of considerable cross-sectional area and reinforced by metal strands or by glass fibers. In the method of the present invention, the reinforcing is obtained by metal composites (3) having very high mechanical strength and very small diameter, said composites extending parallel to the fiber (1).

Abstract: In order to manufacture a fiber by drawing a preform, said preform is made by collapsing a thick-walled silica tube having a reduced pressure established therein and heated in successive passes. The tube is prevented from ovalizing by beginning each pass with a portion bearing against a coaxial internal conical guide. The invention is applicable to low cost fiber manufacture.

Abstract: The antenna includes at least one group of antenna elements (EA1, EA2, . . . , EAp). Microwaves emitted by a central emitter (EH) reach a particular element (EA1 for example) by passing through a controllable phase shifter (VE1), a laser (LE1) which modulates a carrier light signal at a frequency specific to said antenna element with the microwaves, via an optical deflector (FIE) which injects said light signal into an optical waveguide (GE) which is common to all of the antenna elements in the group, via an optical deflector (FPE) which directs said light signal to a detector which is specific to said antenna element (EA1), and which reconstitutes the microwaves, and via a microwave amplifier (AE1) which applies the microwaves to said antenna element. The system is applicable to telecommunications and to radar.

Abstract: Twenty temperature sensors follow one another along a measurement fiber. Each successively reflects a small fraction of the energy of an interrogation light pulse running along said fiber, with the value of the fraction being indicative of temperature. To do this, each sensor is constitutred by a gap between two successive lengths (F2, F3) of an optical fiber, said gap being filled with a transparent glue (36) whose refractive index varies as a fuction of temperature. The interrogation pulse is returned solely by the optical surface constituted by the end face (38) of the upstream length (F2) of the fiber.

Abstract: The active material is constituted by an alkali metal in the zero valent state which alkali metal is inserted into an insertion compound. The insertion compound receiving the alkali metal has an ordered three-dimensional lattice structure and is constituted by at least one intermetallic compound having polyatomic anionic clusters with atoms chosen from the group constituted by gallium, boron and aluminum, and with structuring counter ions chosen from the group constituted by alkaline earth and alkali ions.

Abstract: An electrochemical cell which has a negative electrode (1) including an alkali or alkali-earth metal dissolved in liquid ammonia, a positive electrode (2), an electrolyte (3), and a separator (4). The positive electrode (2) is constituted by a solution in ammonia of a chalcogen or of a chalcogenide or of an emulsion or suspension in ammonia of a solid compound suitable for intercalating the metal of the negative electrode (1). Said electrolyte (3) includes a solution of an iodide of an alkali or alkali-earth metal.The invention is used in the field of reversible high-power electric cells operating at low temperatures.

Abstract: A method of plugging the ends of selected ducts (5) in a ceramic structure (1). A paste (8, 9) is prepared from a powder and a liquid. The powder comprises a glass whose coefficient of expansion is close to that of the ceramic structure. The liquid comprises a solvent, a plasticizer and an additive which reduces the adherence of the paste to a paste applying tool (6, 7). The tool is used to push paste into the ends of the selected ducts and the ceramic structure is subjected to heat treatment to ensure that the paste adheres to the walls of the ducts and then becomes solid.

Abstract: An outer casing (1) and an inner mandrel (2), both of which are cylindrical and are substantially coaxial, with powder (3) for manufacturing the tubular parts (11) filling the space which lies between them, contain a stationary distance piece (5) disposed against a shoulder (4) formed in the upper portion of the mandrel (2) and around the upper portion. A cover (6) also is provided around the upper portion and bears firstly against the upper end of the stationary distance piece (5) and secondly against the end of the casing (1), the cover (6) being hollowed out so as to provide an annular space (7) around the stationary distance piece (5), a moving distance piece (8) being disposed in the space (7) and bearing against the surface of the powder (3) so that during isostatic compression, the upper end of the moulded part (11) can extend into the space (7) while driving the moving distance piece (8).

Abstract: An electric cell with a non-aqueous electrolyte. The cell includes a positive electrode whose active material is suitable for inserting the negative active material dynamically, a negative electrode whose active material includes at least one alkali metal, and an electrolyte, wherein said positive electrode includes at least one compound whose general formula is MX.sub.4 R.sub.n T.sub.p, where M represents an element chosen from among silicon, germanium, tin and lead, X represents sulphur, selenium or tellurium, R and T represent an element chosen from among copper, silver, manganese, iron, cobalt and nickel, n being greater than or equal to 0 and less than or equal to 4, p being greater than or equal to 0 and less than or equal to 2. The invention is used in connection with button type electric cells.

Abstract: Lead accumulator which comprises a plurality of elements each consisting of a negative plate, a positive plate and separating means intercalated between these plates, the said separating means comprising a first and a second microporous separator, between which spacers define channels, characterized in that the thickness of the channels (11) is between 0.5 mm and 2 mm and in that the width of the channels (11) is between 2 mm and 10 mm.Particularly valuable application in traction batteries.

Abstract: In a method of regulating the temperature of a system in which exothermic type reactions take place at temperatures of several hundreds of degrees and which are followed by stoppage periods, the system (1) is put in contact with a first substance (4) whose boiling temperature (T2) is close to the required temperature (T) of the system, and heat which results from the exothermic reactions is used to boil the first substance (4). Thereafter heat which comes from the condensation of the vapor evolved by said boiling is used to heat a second substance (5) to its melting point (T1), the second substance (5) being chosen so that it melts at a temperature close to but lower than the boiling temperature (T2) of the first substance (4). In operation the second substance (5) is kept at a temperature which is substantially constant and a little higher than its melting point (T1) until the end of a period of exothermic reaction.

Abstract: This system includes optical fibers (21,26,49,51) which connect subscriber sets (p,n) to an optical interconnection center (59). An optical frequency F.sub.p and a modulation frequency f.sub.p are ascribed to each subscriber p, these frequencies being specific to the subscriber. The set of each subscriber p includes a laser (19) which delivers a wave (22) of frequency F.sub.p and means (9, 12 to 18) to modulate the amplitude of this wave at the frequency f.sub.n ascribed to the subscriber n with whom he wishes to communicate.

Abstract: The photovoltaic cells (6) are retained and protected by a transparent elastomer layer (12) extruded when hot prior to vulcanization and applied against the cells with a slight pressure to cause it to go into the spaces between cells, and vulcanized by heating, for example at 110.degree. C. or at 180.degree. C., thanks to the presence of incorporated peroxides.Application in the production of electricity from solar energy.

Abstract: A method of manufacturing a dense silicon carbide ceramic includes heat treating an alpha silicon powder in a vacuum to between 1200.degree. and 1400.degree. C., adding a boron powder either before or after heat treating, then, adding a substance containing carbon, milling the mixture, compressing the milled mixture into a desired shape, sintering the formed shape at 2100.degree. C. in an argon atmosphere. The method has particular application to manufacturing parts for gas turbines.

Abstract: An electric cell with a non-aqueous electrolyte. The cell includes a positive electrode whose active material is suitable for inserting the negative active material dynamically, a negative electrode whose active material includes at least one alkali metal, and an electrolyte, wherein said positive electrode includes at least one compound whose general formula is MX.sub.4 R.sub.n T.sub.p, where M represents an element chosen from among silicon, germanium, tin and lead, X represents sulphur, selenium or tellurium, R and T represent an element chosen from among copper, silver, manganese, iron, cobalt and nickel, n being greater than or equal to 0 and less than or equal to 4, p being greater than or equal to 0 and less than or equal to 2. The invention is used in connection with button type electric cells.

Abstract: A secondary electric cell which includes: a non-aqueous electrolyte, a negative electrode whose active material includes at least one alkali metal in contact with the electrolyte, and a positive electrode whose active material is suitable for intercalating the active material of the negative electrode, wherein said positive electrode includes an active compound or solid solution whose general formula is M.sub.x X, R.sub.y X.sub.3 where:M is an element chosen from lead and tin;R is an element chosen from bismuth and antimony; andX is an element chosen from sulphur and selenium, with x having a value lying between 0 and 1 (inclusive), and y having a value lying between 0 and 2 (inclusive). Such cells may be used in watches or pacemakers.