TERMIUM Plus^®

Fiche 1,  Justifications,  Anglais

Record number: 1, Textual support number: 1 DEF

The phenomenon exhibited by laser gyros that is characterized by frequency locking of the clockwise and counterclockwise beams at low input rates.  3, fiche 1, Anglais, - lock%2Din

Record number: 1, Textual support number: 1 CONT

Lock-in is a fundamental physical phenomenon associated with all oscillating devices. Laser gyros exhibit the same phenomenon, in that the coupling mechanism is the reflection of light from one laser beam back along the path where it interacts with the oppositely traveling beam. This is called backscatter and is caused primarily by imperfect mirrors.  4, fiche 1, Anglais, - lock%2Din

Record number: 1, Textual support number: 1 OBS

[Lock-in] is caused by the coupling of energy between the laser beams and results in a threshold error near zero input angular rate unless a corrective means, such as biasing, is used.  3, fiche 1, Anglais, - lock%2Din

Fiche 1,  Justifications,  Français

Record number: 1, Textual support number: 1 CONT

L'origine physique [du] blocage des oscillations [gyromètre laser] tient à ce qu'une partie de chacun des rayonnements se déplaçant dans un sens donné est renvoyée dans l'autre sens; ce renvoi est notamment dû aux irrégularités de surface des miroirs et aux variations d'indice de ces miroirs.  3, fiche 1, Français, - blocage

Record number: 1, Textual support number: 2 CONT

La structure simple du gyrolaser lui confère une excellente fiabilité et une bonne précision [...] Les défauts de surface des miroirs, même infimes, provoquent la rétrodiffusion d'une partie de chaque rayon qui se couple alors avec le rayon se propageant dans l'autre sens. Il se crée ainsi un couplage (lock-in) entre les faisceaux lasers et une zone aveugle pour les vitesses angulaires faibles.  2, fiche 1, Français, - blocage

Fiche 1,  Justifications,  Espagnol

Fiche 2,  Justifications,  Anglais

Record number: 2, Textual support number: 1 DEF

The action of intentionally imposing a real or artificial rate into a laser gyro to avoid the region in which lock-in occurs.  2, fiche 2, Anglais, - biasing

Fiche 2,  Justifications,  Français

Record number: 2, Textual support number: 1 CONT

La zone aveugle et son antidote, l'activation. [...] Il est assez fréquent, notamment en électronique, de constater la synchronisation de deux oscillateurs de fréquences propres très voisines, sous l'effet d'un couplage. Ce phénomène existe dans les gyromètres laser et conduit, en régime permanent, à des courbes d'étalonnages non linéaires [...] Un artifice, appelé activation permet de pallier les inconvénients [...]; ce procédé consiste à faire travailler le gyromètre en permanence ou, à la rigueur, pendant la majeure partie du temps, dans la zone linéaire de sa courbe d'étalonnage traduisant m [(oméga]).  2, fiche 2, Français, - activation

Fiche 2,  Justifications,  Espagnol

Fiche 3,  Justifications,  Anglais

Record number: 3, Textual support number: 1 DEF

One half of the absolute value of the algebraic difference between the two rates defining the region over which lock-in occurs.  2, fiche 3, Anglais, - lock%2Din%20rate

Record number: 3, Textual support number: 1 OBS

lock-in: The phenomenon exhibited by laser gyros that is characterized by frequency locking of the clockwise and counterclockwise beams at low input rates.  2, fiche 3, Anglais, - lock%2Din%20rate

Fiche 3,  Justifications,  Français

Record number: 3, Textual support number: 1 OBS

Voir la fiche «blocage; couplage / lock-in».  2, fiche 3, Français, - taux%20de%20blocage

Fiche 3,  Justifications,  Espagnol

Fiche 4,  Justifications,  Anglais

Record number: 4, Textual support number: 1 CONT

... for a mechanically dithered RLG [ring laser gyro], non-linearities(sidebands) appear in the input-output scale factor curve for an input rotation rate which is a harmonic of the dither frequency... There are two disadvantages to dithering. One is that the rotation rate periodically passes through zero where lock-in occurs. This results in a "random walk" angular position error. The other is that the vibration of the gyro body may affect other components or the gyro may be affected by other vibration sources. The laser gyro need not be mechanically dithered. The same result may be achieved by optical devices.  1, fiche 4, Anglais, - mechanically%20dithered%20RLG

Record number: 4, Textual support number: 1 OBS

dither: To periodically tilt from side to side.  4, fiche 4, Anglais, - mechanically%20dithered%20RLG

Fiche 4,  Justifications,  Français

Fiche 4,  Justifications,  Espagnol

Fiche 5,  Justifications,  Anglais

Record number: 5, Textual support number: 1 CONT

... for a mechanically dithered RLG [ring laser gyro], non-linearities(sidebands) appear in the input-output scale factor curve for an input rotation rate which is a harmonic of the dither frequency... There are two disadvantages to dithering. One is that the rotation rate periodically passes through zero where lock-in occurs. This results in a "random walk" angular position error. The other is that the vibration of the gyro body may affect other components or the gyro may be affected by other vibration sources. The laser gyro need not be mechanically dithered. The same result may be achieved by optical devices.  1, fiche 5, Anglais, - mechanically%20dithered

Record number: 5, Textual support number: 1 OBS

dither: To periodically tilt from side to side.  2, fiche 5, Anglais, - mechanically%20dithered

Fiche 5,  Justifications,  Français

Fiche 5,  Justifications,  Espagnol

Fiche 6,  Justifications,  Anglais

Record number: 6, Textual support number: 1 CONT

One of the more advanced concepts is the laser/fiber-optics gyro. For this gyro a fiber-optics cable up to 300(100 m) in length is coiled many times around a loop, with both ends brought out to a laser. The laser beam is split into two beams, with the beams directed into the opposite ends of the coiled fiber-optics cable. Upon emerging from the opposite ends, they are recombined at the beam splitter to form interference fringes. Unlike the laser gyro, the coiled fiber is not a part of the resonant cavity and hence does not exhibit the lock-in phenomena; however, a rotation rate causes only a fringe displacement and not an integrating effect as in the laser gyro. The instrument is therefore a rate gyro and not a rate-integrating gyro.  1, fiche 6, Anglais, - coiled%20fiber

Fiche 6,  Justifications,  Français

Record number: 6, Textual support number: 1 CONT

Les gaines de protection pour fibre optique (spiralée).  1, fiche 6, Français, - fibre%20optique%20spiral%C3%A9e

Fiche 6,  Justifications,  Espagnol