Abstract: The invention pertains to a frame element of a laser gyroscope comprising a substrate comprising mobile ions and an electrode fixed to the said substrate, comprising at least one electrically conducting element, connected electrically to the said electrode, and furnished with at least one distal part integrated into the said substrate and exhibiting at least one tip and/or at least one groove, forming at least one blind hole and/or at least one groove in the said substrate, of shape corresponding to that of the said distal part or parts, so as to obtain a tip effect.

Abstract: A box includes a lightguide in the form of a thin plate having two opposed main faces and at least two edges, the lightguide having a light-diffusing optical structure on one of the faces. Light-emitting diodes are placed linearly along at least one of the edges of the lightguide, the light emitted by the light-emitting diodes illuminates the lightguide via the edge, and is being diffused by that face of the lightguide having the optical structure. The light emitting diodes placed along each of the edges of the lightguide are organized in at least two rows and in such a way that a light-emitting diode in one row supplied by an electric power supply is immediately followed by a light-emitting diode in the other row supplied by another electric power supply.

Abstract: The invention relates to a light box, intended especially for the backlighting of liquid crystal displays. The box includes a lightguide in the form of a thin plate having two opposed main faces and at least two edges, the lightguide having a light-diffusing optical structure on one of the faces. Light-emitting diodes are placed linearly along at least one of the edges of the lightguide, the light emitted by the light-emitting diodes illuminates the lightguide via the edge, and is being diffused by that face of the lightguide having the optical structure. The light-emitting diodes placed along each of the edges of the lightguide are organized in at least two rows and in such a way that a light-emitting diode in one row supplied by an electric power supply (S1 to S8) is immediately followed by a light-emitting diode in the other row supplied by another electric power supply.

Abstract: A display device comprising a liquid-crystal cell element (20) placed between two polarizers (23, 28) comprising at least one optical structure for compensating for the variations in birefringence of said liquid crystal according to the viewing angle. The optical compensation structure comprises at least one oblique-axis film (25, 26) of polymerized liquid-crystal type suitable for at least partly compensating for the undesirable effects of the natural birefringence of the liquid crystal, combined with a volume hologram (24, 27) of small retardation suitable for improving the compensatability of said film.

Abstract: A grating structure by high dispersion volume holography that applies, for example, to pulse compression or stretching devices. The grating structure includes a transmission volume holographic grating produced on a reflective support. The grating includes strata inclined to the plane of the support, the angle of inclination of the strata defined with respect to the normal to the support and the pitch of the strata being chosen such that a light beam of a predetermined mean wavelength, incident on the structure with a predetermined angle of incidence, undergoes a first passage through the grating, is reflected by the reflective support, undergoes a second passage through the grating, and is only diffracted by the grating during one of the first and second passages.

Abstract: A display device comprising a liquid-crystal cell element (20) placed between two polarizers (23, 28) comprising at least one optical structure for compensating for the variations in birefringence of said liquid crystal according to the viewing angle. The optical compensation structure comprises at least one oblique-axis film (25, 26) of polymerized liquid-crystal type suitable for at least partly compensating for the undesirable effects of the natural birefringence of the liquid crystal, combined with a volume hologram (24, 27) of small retardation suitable for improving the compensatability of said film.

Abstract: The invention concerns a grating structure by high dispersion volume holography and applies, for example, to pulse compression or stretching devices.

Abstract: A display panel having compensation using holographic birefringent films. Due to the natural birefringence of liquid crystals, contrast suffers when a liquid crystal cell is viewed at an oblique incident angle. Compensation devices made of birefringent media are used to correct this deficiency. The compensation devices include at least one film, the birefringence of which is induced by the recording of a volume hologram consisting of parallel fringes. The choice of the optical birefringent axes depends only on the orientation of the fringes so that it is easy to achieve compensation using uniaxial films which are inclined with respect to the plane of the film.

Abstract: Transceiver head for a longitudinal Doppler speed indicator.Transceiver head for a longitudinal Doppler speed indicator with at least one pair of measuring axes.It comprises:a laser (1);polarization switching means (4) on the path of the laser beam;polarization separating means (5) on the path of the polarized beam that comes from the switching means;control means (5) for switching the switching means alternately from one state to another to direct the beam alternately to one measuring axis and then to another depending on its polarization state.

Abstract: The invention is a method for determining anemobaroclinometric parameters on board an aircraft.The air speed vector (Vp), the static pressure (Ps), and the impact temperature (Ti)are measured, and the other parameters are calculated on the basis of the aforementioned measurements.

Abstract: A system is disclosed for measuring the angle of incidence of an aircraft, comprising at least one probe with a laser generator having a monochromatic emission spectral line, an optical emission system, an optical system receiving a monochromatic radiation back-scattered by the aerosols, means for pumping the laser generator, a detection interferometer receiving a part of the emitted laser beam and the back-scattered radiation and means for determining, after beating of the emitted beam and back-scattered beam, the Doppler frequency of the back-scattered beam and deriving therefrom the air speed along the axis of the emitted laser beam, in which system the optical emission system is adapted so as to focus the emitted beam on an air slice distant from the aircraft, the laser generator is disposed in the vicinity of the skin of the aircraft, the pumping means and the interferometer are moved inside the aircraft and the frequency of the laser spectral line is adapted so that the connections between the probe, on

Abstract: A sensor is disclosed for detecting a physical magnitude, comprising a mechanical resonator, adapted to be subjected to a mechanical stress representative of the magnitude to be measured, and means for causing the resonator to oscillate and maintaining its oscillations at a resonance frequency representative of the magnitude to be measured, wherein the resonator is made from a solid laser material and said oscillation means comprise means for feeding the laser resonator with a continuous pumping light beam.

Abstract: A laser anemometer with several measurement directions is disclosed, in which an incident beam (3) is intercepted by two disks (91, 92) having a common axis which are driven in rotation about this axis. The two disks are provided with transparent and reflecting sectors arranged so that the incident beam successively follows three different paths (3x, 3y, 3z). The axis common to the two disks intersects the axis of the incident beam (3). Mirrors reflect the directed beam in mutually orthogonal directions defining a three-dimensional orthogonal reference system in which the three components of the speed may be successively measured. The anemometer of the invention is particularly suitable for the measurement of the three components of the speed of an aircraft with respect to still air.