TERMIUM Plus^®

Fiche 2,  Justifications,  Anglais

Record number: 2, Textual support number: 1 CONT

The laser(or lidar) velocimeter [lidar=light radar] operates in a fashion entirely analogous to that of the airborne Doppler weather radars likely soon to be available for detecting turbulence in storm cells. As with radars, the device detects air movements by observing the motion of particles suspended in the air and carried with it. The only significant difference is that a beam of coherent infrared radiation is used to scan ahead of the aircraft, instead of a beam(or series of pulses) of radio energy in the considerably longer-wavelength microwave band. The frequency of the back-scattered echoes or reflections undergoes Doppler shift detection by standard heterodyning techniques, which involve comparing the frequency of the reflected illumination with that of the original laser beam. Any reflecting object or material which has motion relative to the transmitter/receiver will cause a detectable shift in frequency, which can be isolated from the transmitter's own proper motion(over the ground) and thus yield a precise indication of the speed at which the air is moving several hundred metres in front of the aircraft. From this data, it is easy to compute what the air speed of the aircraft will be when it reaches that particular patch of air in a few seconds’ time [and hence detect possible turbulence ahead].  2, fiche 2, Anglais, - laser%20velocimeter

Fiche 2,  Justifications,  Français

Record number: 2, Textual support number: 1 CONT

Le principe de fonctionnement du vélocimètre à laser (ou lidar) est exactement le même que celui des radars météorologiques Doppler de bord, qui doivent être mis en service prochainement pour la détection des turbulences dans les systèmes d'orages.  1, fiche 2, Français, - v%C3%A9locim%C3%A8tre%20%C3%A0%20laser

Fiche 2,  Justifications,  Espagnol

Fiche 3,  Justifications,  Anglais

Record number: 3, Textual support number: 1 CONT

The germanium plate [of the laser velocimeter] acts as a beam-splitter for diverting the scattered return signal into the detector, while the quarter-wave plate acts as a vertical polarizing screen.  1, fiche 3, Anglais, - vertical%20polarizing%20screen

Fiche 3,  Justifications,  Français

Record number: 3, Textual support number: 1 CONT

La lame de germanium [du vélocimètre à laser] agit comme séparateur de faisceau pour diriger dans le détecteur le signal de retour, tandis que la lame quart d'onde sert d'écran de polarisation verticale.  1, fiche 3, Français, - %C3%A9cran%20de%20polarisation%20verticale

Fiche 3,  Justifications,  Espagnol

Fiche 4,  Justifications,  Anglais

Record number: 4, Textual support number: 1 CONT

[The production version] of the laser velocimeter and its mounting cradle(...) would be considerably smaller, probably with an integral cooling system and greatly simplified spectrum analyzer unit, and could be co-mounted(possible with a chin blister for the laser telescope) together with a weather radar antenna.  1, fiche 4, Anglais, - mounting%20cradle

Fiche 4,  Justifications,  Français

Record number: 4, Textual support number: 1 CONT

Le vélocimètre à laser sur son bâti de montage. Le modèle de série serait considérablement plus petit. Il posséderait vraisemblablement un dispositif de refroidissement intégré et un analyseur de spectre très simplifié. Il pourrait être installé à côté d'une antenne de radar météorologique (avec éventuellement une coupole sous le nez de l'avion pour loger le télescope à laser).  1, fiche 4, Français, - b%C3%A2ti%20de%20montage

Fiche 4,  Justifications,  Espagnol