Abstract: The object of the invention is a single dual reed module, particularly for an instrument of the accordion type using two directions of air flow, characterized in that it comprises, for each note, a single fixed tongue carrier (32) with a window (34) and a tongue (36) connected to this tongue carrier and comprising at least one tongue (42) disposed in line with this window, as well as at least one associated movable element (44), disposed laterally relative to said tongue and adapted to take a first position for a first direction of air flow by providing an interstice between this movable element and the edge of the tongue such that this blade vibrates to emit said note in this first direction of air flow, and a second position symmetrical to the first position relative to the plane of the tongue for the second direction of air flow, by also providing an interstice such that the tongue vibrates to emit the same note in this second direction of air flow.

Abstract: The object of the invention is a single dual reed module, particularly for an instrument of the accordion type using two directions of air flow, characterized in that it comprises, for each note, a single fixed tongue carrier (32) with a window (34) and a tongue (36) connected to this tongue carrier and comprising at least one tongue (42) disposed in line with this window, as well as at least one associated movable element (44), disposed laterally relative to said tongue and adapted to take a first position for a first direction of air flow by providing an interstice between this movable element and the edge of the tongue such that this blade vibrates to emit said note in this first direction of air flow, and a second position symmetrical to the first position relative to the plane of the tongue for the second direction of air flow, by also providing an interstice such that the tongue vibrates to emit the same note in this second direction of air flow.

Abstract: The invention relates to an optical fibre including, over a part of its length, variations of refractive index disposed in plane, parallel and periodic strata, of period I, which are inclined at an angle .alpha. in relation to the axis of the fibre. The normal to the strata forms a non-zero angle with the axis of the fibre. The invention also relates to the application of the invention optical fibre as a selective extractor of flux, a light injector, a coupler, a sensor and a polarizer.

Abstract: This is a system of fibre optic sensors comprising at least one such fibre for measuring a physical or chemical parameter sensitive to the change in an environment (E) within which the sensor is placed, the said fibre comprising a cladding (3), a core (5) surrounded by this cladding, an axis (7) with a length in the direction of this axis, and, locally along its parts (9) with variations in optical thickness forming an optical diffraction grating (10), at least one part of the cladding (3) comprising in its composition an active material whose optical properties vary as a function of the change in the said parameter (P) within the environment where the sensor is placed. The active material may be a heteropolysiloxane.

Abstract: A method and reflectometer used to analyze guided optical components, optical fibers or optical guide networks by time reflectometry in a time sphere. The method comprises steps of creating a light probe signal, feeding the light probe signals into the guide connected to the system, creating a pumped signal, obtaining a backscattered response signal from the system, sampling the backscattered response signal by interacting the pump signal therewith to produce a sampled signal, and receiving the sampled signal with a photodetector, which is blind to the pump signal and the backscattered response signal and will recompose the backscattered response signal from the sampled signal.

Abstract: A device for the control and adjustment of the modal alignment of optical fibers is described. The device includes at least one laser (20) delivering an electromagnetic beam, and at least one mode selector (26) suitable for acting on the beam so as to produce a TEM1, j-1 type modal structure, the modal structure having an axis of symmetry (15). Also included in the device are a marker for marking at this axis of symmetry (15) orientation variations around an axis (RR1); an introducer for introducing the electromagnetic beam into an optical fiber (10); and a measurer (36) for measuring luminous power. The device is particularly adapted for the adjustment of the alignment of optical fibers as regards their connection and for centering an optical fiber in a plug connector.