Abstract: A plasma reactor for performing an etching or deposition method, said reactor including a vacuum enclosure designed to receive a substrate to be treated, and including means for inserting a gas to be ionized, the plasma, which is produced in a container, being excited by an antenna fed by a radio-frequency power generator, wherein said antenna is composed of an electrical conductor that constitutes a single circular loop having two diametrically-opposite points connected to feed conductors.

Abstract: A leak-detection installation for testing the gastightness of flexible or rigid sealed packages containing a certain concentration of tracer gas, said installation including a belt conveyor, a bell-shaped cover situated above said conveyor and including drive means enabling said cover to be raised and to be lowered until it bears against the belt of said conveyor, said cover being connected to a tracer gas leak detector, the resulting assembly being controlled by control electronic circuitry, wherein said belt is made of a material that is both non-porous and non-perforated, and wherein the cover carries sealing means at its bottom periphery for co-operating with the belt of said conveyor to guarantee the gastightness of said cover when it is in the low position, wherein the cover is connected to a vacuum pump, and wherein a backing plate provided with a system of sealing rings is disposed under said belt and in alignment with said cover, said backing plate having a recess and being connected to said cover vi

Abstract: An input signal provided by a generator is applied to a laser emitting diode via a predistortion circuit for improving the linearity of the response of the source. The predistortion circuit includes a linear pi attenuator member constituted by resistances and a non-linear compensating element constituted by a Schottky diode connected in parallel with said attenuator member. The invention is particularly applicable to making light transmitting cable heads for optical fiber telecommunications systems.

Abstract: The machine includes a piston which is cylindrical in the mathematical sense, which has an axis .DELTA..sub.p, which is rotary, and which is situated in a cylindrical casing that has an axis .DELTA..sub.c, the piston having an outline that has .DELTA..sub.p axes of symmetry, the casing delimiting a hollow volume whose cross-section in a plane perpendicular to its axis .DELTA..sub.c has S.sub.c axes of symmetry, S.sub.p and S.sub.c differing from each other by unity. The axes .DELTA..sub.p and .DELTA..sub.c are parallel and are separated by a distance E, the piston and the casing delimiting at least three chambers between them, and the casing including at least one suction inlet and one delivery outlet. The positive-displacement machine further includes a ferromagnetic sprocket which has an axis .DELTA..sub.p, which is secured to the piston, which has N.sub.p teeth, and which is disposed inside a ferromagnetic toothed ring which has an axis .DELTA..sub.

Abstract: A data communication system comprises two links between two terminal equipments, a standby link being used in the event of malfunctioning of a normal link. A method of returning to the normal link after using the standby link comprises, in parallel with transmission on the standby link, preliminary verification of the continuity of the normal link. The preliminary verification involves simultaneous transmission of a data signal by the terminal equipment initiating the continuity verification procedure, on the normal link and on the standby link, and detection by the other terminal equipment of the presence or absence of power on the normal link. This is done for each transmission medium of the normal link if the latter comprises separate media for each transmission direction.

Abstract: A rotation tuned optical filter comprises a Fabry-Perot type interferometer disposed between an optical source and an optical receiver. The interferometer filters an input optical signal from the optical source. The input optical signal propagates substantially in a single mode. The interferometer supplies a filtered optical signal to the optical receiver which comprises a receiving surface which integrates the power density of the filtered optical signal. The filter comprises means for modifying the position of the filtered optical signal relative to the receiving surface of the optical receiver.

Abstract: This device essentially comprises:first and second connection ports (R1, R2) for said optical link,first, second and fourth supports (S1, S2, S4) adapted to support first, second and third opto-electronic transducer means, respectively, andthird and fifth supports (S3, S5) adapted to support first and second beam switching means, respectively, these components being located in a common structure (S) and disposed relative to each other to enable optical transmission between said first connection port R1 and said first beam switching means, between each of said first and second opto-electronic transducer means and said first beam switching means, between said second port R2 and said second beam switching means, between each of the two switching means and between said third opto-electronic transducer means and said second switching means, so defining within said structure first, second, third, fourth, fifth, sixth and seventh optical transmission channels (V1, V2, V3, V4, V5, V6, V7).

Abstract: In a method of allocating time slots for transmission in a half-duplex time division multiple access point-to-multipoint bidirectional transmission system enabling transmission between a central station and a plurality of remote stations at least one time slot is allocated to each remote station and to each transmission direction. The set of all time slots used for transmission from the central station to the remote stations are grouped into downward frames and the set of all time slots used for transmission from the remote stations to the central station are grouped together in upward frames. The origin time of the upward frame is chosen in each remote station so that in the central station the origin time of the frame is separated from the end time of downward frames by a period less than twice the transmission time between the remote station and the central station, whereby there is defined in the remote station an overlap area between upward and downward frames.

Abstract: An optical communication link with correction of non-linear effects comprises an optical fiber transmission line subject to chromatic dispersion and non-linear effects and correction means for limiting the disadvantageous consequences of this dispersion and/or these non-linear effects. The correction means comprise at the output of the transmission line a dispersion compensator adapted to apply dispersion in the opposite direction to and of lower absolute value than the dispersion due to the transmission line.

Abstract: A helium leak detector includes a gas analyzer and a secondary pump having at least on its discharge side a Holweck type stage. The pump is of a type enabling the suction pressure to be reduced to a value at least equal to 10.sup.-4 mbar and a discharge pressure which is sufficiently high to be compatible with the suction pressure of a dry primary pump having at least two stages. The secondary pump is connected to the low-pressure output of a sampling unit on an intermediate point of the secondary pump where the flow conditions are molecular. A sniffer probe is connected to the high-pressure side of the sampling unit. This high-pressure side is further connected to the dry primary pump between its at least two stages.

Abstract: In a method of coupling an optical fiber to an optical component on the same substrate, eccentricity of the core of a coupling fiber is exploited to adjust the vertical position of the core by rotation of the fiber about its axis. This adjustment is carried out with the fiber held in contact with a horizontal reference surface of a substrate also carrying a laser diode constituting the component to which the fiber must be coupled. The method can be used to implement transmission headers for optical fiber telecommunication systems.

Abstract: A photonic concentrator is used to connect to a telecommunication network subscriber terminals sending and receiving data in the form of fixed length cells using asynchronous time-division multiplexing, in particular on an optical fiber. The concentrator comprises, for processing cells from a subscriber terminal, a time-division and non-synchronous statistical spectral multiplexing stage, a synchronization to a local clock stage, a spectral multiplexing and bit rate converter stage, and a periodic time-division multiplexing stage. To process cells addressed to subscriber terminals it comprises a periodic time-division demultiplexing, spectral multiplexing and bit rate adjuster stage, a bit rate converter stage and a spectral demultiplexing stage. The concentrator has applications in telecommunication networks.

Abstract: A multiplexer and a demultiplexer time-division multiplex and demultiplex binary data in the form of cells having a fixed number of bits. For example, to time-division multiplex cells comprising 424 bits the original bit rate of a block of 16 bits of a cell is multiplied by four, each cell being divided into a series of 27 blocks. The blocks constituting each cell are concatenated after their bit rate has been multiplied. Similarly, the demultiplexer divides the bit rate by dividing each cell into blocks, separating consecutive blocks by a gap and dividing the bit rate successively in each block. The multiplexer and demultiplexer have applications in time-division multiplex telecommunication networks.

Abstract: A method for determining the transmission time between remote terminal stations and a central terminal station in a point-to-multipoint bidirectional transmission network. The central station measures the time interval between a reference time for sending of information signals by the central station and reception by the central station of a location signal sent by a remote station after a time-delay starting from a reference time for reception of information signals by the remote station so that the location signal is received by the central station in a predetermined location window not assigned to reception of information signals by the central station. For a given remote station the time-delay is variable from an initial value such that the location signal is not necessarily received in the window and the location signal sending by the remote station is then repeated until the location signal is received by the central station in the window.

Abstract: A device for associative coding of printed circuit boards comprises a coding member comprising a central longitudinal member, attachment arms and a series of appendages the spacing between which is equal to the spacing between two board guide slideways. The front panel of each board incorporates a coding slot enabling an appendage to pass through it when the latter is aligned with the slot. The position of the coding slot is a characteristic common to all boards of a given family. After a first board is fitted into the subrack only other boards of the same family can be connected into the part of the subrack fitted with the coding member. This prevents the insertion into the same subrack or subrack compartment of boards from different and incompatible families although for a same product type and having the same functionality.

Abstract: The present invention relates to a pumping installation for pumping out an enclosure containing gases which are mixed with solid particles or which generate solid condensates or particles, said installation including a pump equipped with a feed system for supplying an inert purge gas, the pump having its exhaust orifice connected to an evacuation duct, wherein said evacuation duct is connected to said exhaust orifice via a static particle-separator device whose driving flow is solely the exhaust flow of the pump.

Abstract: The source includes an electro-absorption modulator receiving a continuous light wave supplied by a laser emitter 10. The characteristic response curve of the modulator has a threshold so that the modulator transmits an optical pulse having a duration which is less than the duration of an electrical control pulse which is applied to the modulator by a control generator. Soliton-type optical pulses obtained in this way are transmitted via a line fiber to a receiver. Application to optical transmission.

Abstract: Each upright of an electronic, especially telecommunication equipment rack comprises an outer profile and an inner profile delimiting a hollow interior volume used to run connections along equipment supported by said uprights. The profiles are such that the interior volume has in the heightwise and depthwise directions an opening accessible from the front side of the rack providing easy access to the connections along all of their path between the points at which they enter and leave the interior volume.

Abstract: A photonic switching matrix comprises a plurality of wavelength converters at respective inputs of the matrix to assign a wavelength to each cell applied to an input of the matrix. An optical buffer common to all the outputs of the matrix stores each cell for a duration selectable between 0 and k.T.sub.c where k is an integer and T.sub.c is the duration of cell. A space routing stage comprises a filter for each output of the matrix passing to a given output only cells having a given wavelength. The converters and the buffer are controlled according to routing information indicating for each cell the output of the matrix to which said cell is addressed and for selecting the duration for which each cell is stored in the buffer so as to construct a queue for each output to avoid conflicts between two cells to be switched to the same output presented at the same time as the input of the switching matrix. The switching matrix has applications in telecommunication networks.

Abstract: An electromagnetic bearing including a stator portion having sixteen magnetic cores facing the rotor portion. The sixteen cores are divided into four groups of four cores, and each group is equipped with suspension electric windings disposed such that the magnetic flux produced thereby is in the same direction in the first two cores of the group and in the opposite direction in the following two cores, each core in each group further being equipped with a position-detection electric coil, the coils on the four cores in any one group being connected together in series and powered by an AC electric current, the magnetic flux produced by the coils at any determined time being in opposite directions in the first two cores of any group, and also in opposite directions in the following two cores.