Abstract: The present invention relates to a method for self-testing an angle-of-attack probe comprising the steps of controlling an angular excitation of a rotary element that is rotatable about its equilibrium position according to known excitation characteristics; acquiring angular measurements relating to the rotation of the rotary element, determining a parasitic torque applied to the rotary element on the basis of the angular measurements and of the excitation characteristics; comparing at least one component of the parasitic torque with at least one predetermined threshold and detecting an operating fault in the probe when said component exceeds the predetermined threshold.

Abstract: A method for identifying an obstacle (O) in the laser beam (F) of a lidar system includes: commanding the transmission of a laser beam (F); and receiving a lidar signal (S) corresponding to the reflection of the beam (F) on a diffuser present in the beam (F). The detection method further includes: evaluating a set of first parameters of the lidar signal, the set of first parameters including at least an amplitude and a duration, a first detection moment being defined for the lidar signal (S), the duration being defined at each moment as the time elapsed since the first detection moment; identifying an obstacle (O) present in the beam (F) when the amplitude is greater than a first threshold and the duration is greater than a second threshold; and decreasing the power of the beam (F).

Abstract: An airborne compact anemometric lidar system includes a laser that can emit a laser beam, an optical system suitable for forming the laser beam emitted by the laser, an optical window that is transparent to the laser radiation emitted by the laser, wherein the lidar system comprises a first prism and a second prism, the first prism being fixed and configured to deflect the laser beam formed by the optical system, the second prism being mounted on a rotation device configured to perform a rotation about the axis of propagation of the laser beam transmitted by the first prism, so that a laser beam deflected by the second prism passes through the optical window by forming, with the normal {right arrow over (n)} to the optical window, a non-zero angle, the angle between the optical axis of the optical system and the normal {right arrow over (n)} being less than 10°, the rotation device being driven by a circuit that makes it possible to orient the second prism so as to select the angle with which the laser beam p

Abstract: A method for determining the speed vector ({right arrow over (Vd)}), with respect to the surrounding air, of a rotary wing aircraft (HL) equipped with a beam scanning Doppler laser anemometry device for measuring (Step1) a set of projections (Vm) of said speed vector ({right arrow over (Vd)}) in at least four non-coplanar directions, comprising the following steps: detecting (Step2) any anomaly of at least one element from the set of measured projections (Vm), from a comparison with respect to a first threshold (S1), of a deviation between the measurements (Vm) and the measurements (Vp) predicted from a predetermined model depending on values of beam scanning parameters of the anemometry device; and reducing (Step3) the effect of a detected anomaly by invalidating measurements corresponding to said anomaly and computing the components of the speed vector from valid measurements.

Abstract: A method for identifying an obstacle (O) in the laser beam (F) of a lidar system includes: commanding the transmission of a laser beam (F); and receiving a lidar signal (S) corresponding to the reflection of the beam (F) on a diffuser present in the beam (F). The detection method further includes: evaluating a set of first parameters of the lidar signal, the set of first parameters including at least an amplitude and a duration, a first detection moment being defined for the lidar signal (S), the duration being defined at each moment as the time elapsed since the first detection moment; identifying an obstacle (O) present in the beam (F) when the amplitude is greater than a first threshold and the duration is greater than a second threshold; and decreasing the power of the beam (F).

Abstract: The general field of the invention is that of Doppler lidars intended to measure the speed of a target. The lidar according to the invention comprises: First means for modulating the optical frequency of the transmission signal, said frequency being the sum of a constant frequency and of a variable frequency of determined amplitude modulated by a periodic temporal function; Second means for computing the spectrum of the measured heterodyne signal and for creating two measurement spectra obtained by shifting the spectrum of the heterodyne signal by a positive and negative frequency value, said realignment frequency equal to the difference between the instantaneous frequency of the transmission signal and the frequency of a signal transmitted at a time shifted by the round-trip travel time between the lidar and the target; Third means for comparing the two measurement spectra, the difference in amplitude between the two spectra at the Doppler frequency determining the direction of the speed of the target.

Abstract: The general field of the invention is that of optical lidars comprising an optical porthole and operating at a first wavelength. The optical porthole of the lidar according to the invention comprises a layer or a sheet made of an optical material. The lidar comprises means for illuminating said layer or said sheet at a second wavelength different from the first wavelength, said material being transparent at the first wavelength and absorbent at the second wavelength, said second wavelength being located in the visible spectrum.

Abstract: The general field of the invention is that of Doppler lidars intended to measure the speed of a target. The lidar according to the invention comprises: First means for modulating the optical frequency of the transmission signal, said frequency being the sum of a constant frequency and of a variable frequency of determined amplitude modulated by a periodic temporal function; Second means for computing the spectrum of the measured heterodyne signal and for creating two measurement spectra obtained by shifting the spectrum of the heterodyne signal by a positive and negative frequency value, said realignment frequency equal to the difference between the instantaneous frequency of the transmission signal and the frequency of a signal transmitted at a time shifted by the round-trip travel time between the lidar and the target; Third means for comparing the two measurement spectra, the difference in amplitude between the two spectra at the Doppler frequency determining the direction of the speed of the target.

Abstract: Optical system has a passive optical chip on the top surface with a first wave guide and a laser diode arranged on the edge of the chip. The chip has a reflecting structure on the top surface at the wavelength of the laser diode and a thin layer portion powered by the laser diode and covering a part of the first wave guide. The first wave guide input is linked to the laser diode, passing through the reflecting structure. The chip has a second wave guide on the top surface, a first coupler formed by two first portions of the first wave guide not covered by the thin layer portion and situated on either side of the thin layer portion along the optical path, and a second coupler formed by two second portions, respectively of the first and second wave guides, not covered by the thin layer portion.

Abstract: The general field of the invention is that of optical lidars comprising an optical porthole and operating at a first wavelength. The optical porthole of the lidar according to the invention comprises a layer or a sheet made of an optical material. The lidar comprises means for illuminating said layer or said sheet at a second wavelength different from the first wavelength, said material being transparent at the first wavelength and absorbent at the second wavelength, said second wavelength being located in the visible spectrum.

Abstract: A method for determining the speed vector ({right arrow over (Vd)}), with respect to the surrounding air, of a rotary wing aircraft (HL) equipped with a beam scanning Doppler laser anemometry device for measuring (Step1) a set of projections (Vm) of said speed vector ({right arrow over (Vd)}) in at least four non-coplanar directions, comprising the following steps: detecting (Step2) any anomaly of at least one element from the set of measured projections (Vm), from a comparison with respect to a first threshold (S1), of a deviation between the measurements (Vm) and the measurements (Vp) predicted from a predetermined model depending on values of beam scanning parameters of the anemometry device; and reducing (Step3) the effect of a detected anomaly by invalidating measurements corresponding to said anomaly and computing the components of the speed vector from valid measurements.

Abstract: A device for determining the presence of damage or dirt on a Doppler laser anemometry probe (2) porthole (1) comprising means (6) for implementing a continuous angular scan of the laser beam, means (7) for determining a current spectral component of the output signal of the probe (2) corresponding to a parasitic signal due to parasitic reflections on the path common to the emitted wave and the wave backscattered by the medium during spectral analysis of the anemometric signal, and means (8) for comparing said current spectral component of the current parasitic signal with a reference spectral component of the reference parasitic signal.

Abstract: A method for estimating the transverse component Vtrans of the velocity of the air comprises the following steps: emitting a focused laser beam; acquiring an electrical signal resulting from the transit of a particle across the beam at a point of transit; analyzing the signal so as to obtain a spectrogram revealing an elongate mark representative of the transit; estimating the duration of traversal of the laser beam by the particle and the slope of the mark; deducing from the duration and from the slope the distance between the point of traversal of the beam and the focusing point; determining the radius of the beam at the point of transit; deducing the transverse component from the radius and from the duration.

Abstract: A device for characterizing the nature of an aerodynamic stream along a wall, the device including multiple temperature-sensitive optical nodes of Bragg grating type distributed along an optical fiber. The device determining the variations in speed of the aerodynamic stream. The nodes are distributed along a fiber placed substantially following the route of a streamline, and the device processing so as to differentiate the temporal and spatial characteristics of the signals of thermal flowrate among the nodes.

Abstract: A method for estimating the transverse component Vtrans of the velocity of the air comprises the following steps: emitting a focused laser beam; acquiring an electrical signal resulting from the transit of a particle across the beam at a point of transit; analysing the signal so as to obtain a spectrogram revealing an elongate mark representative of the transit; estimating the duration of traversal of the laser beam by the particle and the slope of the mark; deducing from the duration and from the slope the distance between the point of traversal of the beam and the focusing point; determining the radius of the beam at the point of transit; deducing the transverse component from the radius and from the duration.

Abstract: Optical signal emission system comprising a passive optical chip (6) and a laser diode (2) disposed at the boundary of said passive optical chip (6), said passive optical chip (6) being furnished with a reflecting structure (5) in upper surface, of a waveguide (7) in upper surface, passing through said passive optical chip (6), linked to the output of said laser diode (2) and passing through said reflecting structure (5), and of an active or non-linear thin layer portion (8) powered by said laser diode (2), covering a part of said waveguide (7), between said laser diode (2) and said reflecting structure (5).

Abstract: Optical system has a passive optical chip on the top surface with a first wave guide and a laser diode arranged on the edge of the chip. The chip has a reflecting structure on the top surface at the wavelength of the laser diode and a thin layer portion powered by the laser diode and covering a part of the first wave guide. The first wave guide input is linked to the laser diode, passing through the reflecting structure. The chip has a second wave guide on the top surface, a first coupler formed by two first portions of the first wave guide not covered by the thin layer portion and situated on either side of the thin layer portion along the optical path, and a second coupler formed by two second portions, respectively of the first and second wave guides, not covered by the thin layer portion.

Abstract: An optical anemometric probe includes a laser source emitting a linearly polarized primary light beam and an optical block having splitting means for separating the primary beam, an optical reference pathway, an optical emission pathway and an optical measurement pathway. The optical block includes optical means of rotation of the polarization arranged at the output of the laser source and before the splitting means. The optical emission pathway has an optical circulator, a first optical emission/reception head illuminating a first measurement zone, and a second optical emission/reception head illuminating a second measurement zone. The optical circulator has four ports, e.g., a first input port, a second and a third input/ouput port linked respectively to the first optical head and to the second optical head, and a fourth port linked to the optical measurement pathway.

Abstract: A device for characterizing the nature of an aerodynamic stream along a wall, the device including multiple temperature-sensitive optical nodes of Bragg grating type distributed along an optical fiber, and means for determining the variations in speed of the aerodynamic stream. The nodes are distributed along a fiber placed substantially following the route of a streamline, and processing means are devised so as to differentiate the temporal and spatial characteristics of the signals of thermal flowrate among the nodes.

Abstract: The subject of the present invention is a laser anemometry probe for optical homodyne detection of frequency offset by Doppler effect, comprising two devices (DERF1, DERF2) for transmitting/receiving beams in two different directions, avoiding duplicating a plurality of elements of a mono-axial laser anemometry probe.