pulsed 1.5 μm lidar for aircraft wake vortex detection ... - wakenet.ppt

Office National d’études et de Recherches Aérospatiales - De la science vers lindustrie 1.55μm Pulsed Fiber lidar for wake vortex detection (axial or transverse) Agnes DOLFI-BOUTEYRE, Beatrice AUGERE, Matthieu VALLA, Didier GOULAR, Didier FLEURY, Guillaume CANAT, Christophe PLANCHAT, Thierry GAUDO, Claudine?BESSON Jean-Pierre?Cariou, Olivier Petilon, Julius Lawson-Daku L. Bricteux , S.?Brousmiche, S Lugan, B?. Macq Advantages of 1.55 μm fiber systems Low electrical consumption : Electrical to optical efficiency of the order of 10% Wavelength most favourable for eyesafe LIDAR designs IR fiber technology reliability easy to adjust mechanically reliable in a vibrating environment 1.5 μm fiber coherent LIDARs have been successfully in flight operated Compactness Flexibility in terms of onboard installation subsystems spatially far apart in the aircraft body linked together using fiber optics Coherent Doppler LIDAR principle Onboard Axial detection : FIDELIO project Axial detection FIDELIO modeling FIDELIO modeling FIDELIO : modeling conclusions At medium range (1 km), the vortex is easier to detect by measuring the spectrum broadening. These results confirm the IWAKE conclusions Longer pulse duration (800 ns) gives better results than the nominal value of 400ns and leads to a high velocity resolution The vortex is easier to detect at old ages than at young ones, since dissipation increases the velocity dispersion on the observation axis. Low PRF cannot be compensated by increasing the laser energy. Indeed a high PRF value enables incoherent summation, reducing speckle effect and therefore gives a better velocity resolution. For PRF=4 kHz, E=1 mJ, nominal atmospheric conditions: the theoretical LIDAR range is 2400 m. For PRF=10 kHz, E=0.1 mJ: the theoretical LIDAR range is 1200 m. FIDELIO : laser research results Axial detection : lidar architecture FIDELIO :Field tests FIDELIO :Field tests FIDELIO :Field tests Axial detection FIDELIO: Concl