Gyroscope, Ring, External Mirror
Tuesday, September 05, 2006
A Laser Ring Gyroscope has been designed and developed consisting of a closed optical cavity in a three or four-sided block of low-expansion-coefficient material. External Mirrors are mounted at the corners defining the Gyroscope’s laser light beam path. The laser light beam travels through holes bored in the block, which contains a low-pressure sealed in gas. The low-pressure gas, a helium-neon mixture could be used so that the Gyroscope itself can be a Laser. No external light source would be required.
The laser light beams propagate both clockwise and counterclockwise resulting in the two light beams resonating in the same cavity but in opposite directions. Light from both laser light beams is transmitted through one of the mirrors to a photodetector. During gyroscope rotation about the gyroscope’s input axis, changing interference pattern (fringes) occurs since the beams are phase-shifted relative to each other. The photodetector has two sensitive elements for both up counting and down counting of the frequency difference. This frequency counting determines rotation rate and rotation direction. A measurement of angular position is obtained by counting pulses (fringes).
The mirrors should be of high quality to minimize backscatter between the two laser light beams. Backscatter lock-in can be avoided by the use of a dither motor about the gyroscope’s input axis. High-performance Ring Gyroscopes require a path-length compensation device and one of the corner mirrors is adjustable. This adjustment insures that the Gyroscope performance is insensitive to changes in the optical cavity length.
Source: Various Publications
Reference: None Available
Industrial Products
posted by JD52 @ 10:12 PM,
