Abstract: The general field of the invention is that of optical devices designed for measuring anemometer parameters such as speed and temperature, the device being mounted on an aircraft and comprising an optical emission module illuminating the outside air, an optical reception module capable of receiving the light scattered by the air molecules, optical means forming a reference path and computing means connected to the reception module. The optical reception module comprises optical mixing means for mixing a portion of the beam originating from the reference path and a portion of the scattered light beam. The optical emission and reception means are arranged so that the reception device collects the light originating from the Brillouin-Mandel'shtam scattering.

Abstract: The invention relates to a method of protecting aircraft in flight against clear air turbulence (CAT). Consider an aircraft occupying a position P and moving horizontally at a speed V, a plane PH0 being the horizontal plane passing through P. According to the invention, the method includes performing at least one pair of evaluations of air temperature TB, TC at two points B, C which have positions that are symmetrical relative to the plane PH0. At least one pair of horizontal air speed evaluations are performed VHB, VHC at the two points B, C; An air temperature gradient is determined; A horizontal air speed gradient is determined; An index signifying a presence of CAT is determined; The preceding steps are repeated; A trend is analyzed over time of the index.

Abstract: The invention relates to a method of protecting aircraft in flight against clear air turbulence (CAT). Consider an aircraft occupying a position P and moving horizontally at a speed V, a plane PH0 being the horizontal plane passing through P. According to the invention, the method includes performing at least one pair of evaluations of air temperature TB, TC at two points B, C which have positions that are symmetrical relative to the plane PH0. At least one pair of horizontal air speed evaluations are performed VHB, VHC at the two points B, C; An air temperature gradient is determined; A horizontal air speed gradient is determined; An index signifying a presence of CAT is determined; The preceding steps are repeated; A trend is analyzed over time of the index.

Abstract: The invention relates to a radial slaving method and to a reproduction device implementing it for optical discs. In an optical head of a conventional reproduction device using a four-quadrant detector with four photodiode is distributed on either side of a direction parallel to the axis of the track, the individual signals of the photodiodes (d1 to d4) are combined in order to obtain read signals along the two diagonals (diag1, diag2) by subtraction (21, 22). A phase comparison signal circuit (100) makes it possible to construct a radial error signal (Sr) by measuring the phase shift of the diagonal read signals. The invention applies in particular to phase discs with slightly phase-shifting marks.

Abstract: The field of the invention is that of devices for detecting non-metallic objects concealed on human subjects. These devices are more particularly dedicated to the surveillance and protection of reserved access areas, such as airport areas. The device according to the invention comprises a portable detector comprising a transmitter and a receiver of microwave frequency signals disposed in an enclosure of chaotic geometry including a plurality of measurement holes. The microwave frequency signal measured by this detector depends on the nature of the objects disposed under the holes. A processing device linked to this detector is used to correlate the measured signals with prerecorded signals. When the correlation exceeds a certain threshold corresponding to the presence of suspect objects, an alarm is generated.

Abstract: The field of the invention is that of devices for detecting objects concealed on human subjects. These devices are more particularly dedicated to the surveillance and protection of airport areas and transport airplanes. Currently, the devices rely either on X-ray detection or on microwave imaging. In the former case, the system can prove hazardous to human beings, and in the other case, the device raises ethical problems. The invention proposes a device whose operation relies on the reflective properties of the microwave signals polarized by the suspect objects that we are seeking to detect. This device can be portable or installed on security gates. This technique is simple to design, inexpensive, does not require any great computing power and is very well suited to the objects to be detected. The complete measurement is extremely quick and requires no sophisticated measuring instrument.

Abstract: The present invention relates to a fiber-optic gyrometer including a Sagnac interferometer using two light waves propagating in opposite directions in a interferometer loop including a photodetector which delivers an electrical signal Ud representing the light intensity of the interference between the two waves, and for optically phase-shifting the waves controlled by a square-wave modulation signal Um suitable for controlling an optical phase variation at a frequency FO substantially equal to 1/(2to), where to is the propagation time of a wave through the guide. The photodetector is connected to at least a first sampling circuit and a second sampling circuit which are controlled in phase opposition by a clock. The gyrometer includes a means for inverting the phase of the clock at a frequency f, which is very much less than the frequency FO.

Abstract: The field of the invention is that of devices for detecting non-metallic objects concealed on human subjects. These devices are more particularly dedicated to the surveillance and protection of reserved access areas, such as airport areas. The device according to the invention comprises a portable detector comprising a transmitter and a receiver of microwave frequency signals disposed in an enclosure of chaotic geometry including a plurality of measurement holes. The microwave frequency signal measured by this detector depends on the nature of the objects disposed under the holes. A processing device linked to this detector is used to correlate the measured signals with prerecorded signals. When the correlation exceeds a certain threshold corresponding to the presence of suspect objects, an alarm is generated.

Abstract: The invention concerns a recording medium for optically readable data of the multilayer type, a method for making same and an optical system for reproducing said data for reading the medium. The medium (Sb) comprises a stack of layers (C1 to CN) whereof the interfaces constitute planes (P1 to PN) bearing slightly phase-shifting information elements. Said planes generate a relatively significant disturbance of the transmitted beam while diffracting only a very small part of the light passing through them. The reading beam (FI) is focused on the bearing plane and reading is performed by transmission. The disturbances caused by the neighboring defocused layers are eliminated by far field detection of only the low spatial frequencies in the transmitted beam. The invention is particularly useful for very high capacity data optical storage.

Abstract: The invention relates to the field of devices for measuring a nonreciprocal effect and especially to the field of fiber-optic gyrometers. Disclosed a device for measuring a nonreciprocal effect comprising a light source, a monomode spatial filter, a Sagnac ring having two branches, a light splitter, and a light detector. The splitter is a polarization splitter. The filter is nonpolarizing. The detector includes a system for analyzing the polarization state. The light splitter devides the light over branches of the ring. The invention can be applied to other devices for measuring a nonreciprocal effect, especially fiber-optic magnetometers.

Abstract: The method in accordance with the invention consists in illuminating with coherent light a volume-wise at least partially scattering surface of reference objects under specified illumination conditions, in recording the speckle patterns thus obtained for various nominal values of illumination parameters and in a range of values around these nominal values, then, upon the verification of other objects or of the same objects, in illuminating these objects under the same nominal conditions and in comparing each time the speckle pattern thus obtained with those which were recorded and in retaining the objects if their speckle pattern corresponds to one of those that was recorded.

Abstract: Unlike customary vibrating mass gyros which operate by exciting a first fundamental mode of vibration of the vibrating mass and by detecting the effect of the Coriolis force on a second fundamental mode of vibration of the vibrating mass orthogonal to the first mode, this gyro operates by giving its suspended mass a circular motion alternately in the forward and reverse directions and by deducing the gyrometric effect from the difference between the apparent frequencies of the circular motion of the suspended mass in one direction and in the other. This allows a considerable reduction in the drafting of the heading measurement obtained with this type of gyro.

Abstract: In a collective method of fabricating liquid crystal cells on a silicon substrate, a sealing frame for assembling a back electrode substrate and an active matrix circuit silicon substrate is disposed so as to overlap external contact pads of the active matrix circuit and a portion of a connection mechanism provided on the back electrode substrate including the connection mechanism is overhanging with respect to the active matrix substrate, allowing the connection to an external control device.

Abstract: The invention relates to a radial slaving method and to a reproduction device implementing it for optical discs. In an optical head of a conventional reproduction device using a four-quadrant detector with four photodiode is distributed on either side of a direction parallel to the axis of the track, the individual signals of the photodiodes (d1 to d4) are combined in order to obtain read signals along the two diagonals (diag1, diag2) by subtraction (21, 22). A phase comparison signal circuit (100) makes it possible to construct a radial error signal (Sr) by measuring the phase shift of the diagonal read signals. The invention applies in particular to phase discs with slightly phase-shifting marks.

Abstract: Unlike customary vibrating mass gyros which operate by exciting a first fundamental mode of vibration of the vibrating mass and by detecting the effect of the Coriolis force on a second fundamental mode of vibration of the vibrating mass orthogonal to the first mode, this gyro operates by giving its suspended mass a circular motion alternately in the forward and reverse directions and by deducing the gyrometric effect from the difference between the apparent frequencies of the circular motion of the suspended mass in one direction and in the other. This allows a considerable reduction in the drafting of the heading measurement obtained with this type of gyro.

Abstract: The present invention relates to a fiber-optic gyrometer comprising a Sagnac interferometer using two light waves (S1, S2) propagating in opposite directions in a ring waveguide (2), comprising a photodetector (4) which delivers an electrical signal Ud representing the light intensity of the interference between the two waves, and means (5) for optically phase-shifting the waves controlled by a square-wave modulation signal Um suitable for controlling an optical phase variation at a frequency FO substantially equal to ½.t0, where to is the propagation time of a wave through the guide (2).

Abstract: A quantum encryption device comprises a transmitter and a receiver between which an encrypted piece of information is transmitted. The transmitter comprises at least means to send a first packet of photons and an information photon to the receiver, the appearance of the information photon following the packet being lagged by a period of time &tgr; according to a law of probability. The transmitter also comprises means for the encoding of the information photon. The receiver comprises at least means for the encoding of a second packet of photons coming from the first packet and substantially lagged by the period of time &tgr; with respect to this packet, and interference means to make an information photon interfere with the second packet of photons. These interference means provide a packet of photons to create a quantity of photons substantially equal to ±2 times the variance of the noise due to the second packet. The invention can be applied to the industrial-scale making of encryption systems.

Abstract: The invention relates to the field of devices for measuring a nonreciprocal effect and especially to the field of fiber-optic gyrometers.

Abstract: The invention concerns a recording medium for optically readable data of the multilayer type, a method for making same and an optical system for reproducing said data for reading the medium.

Abstract: An anti-piracy recording disk. The disk includes a main recording track which has interruptions or changes of turn. This gives rise to non-sequential reading and therefore to information which is difficult to access. The copying of such a disk by conventional means is very difficult making it possible to easily detect counterfeits or to render any copy unusable.