Transcript Fiber Optic Gyroscope (FOG)

Fiber Optic Gyroscope
(FOG)
Author : Brad Watanabe
Mechanical Gyroscope
 http://www.youtube.com/watch?v=IEwAry0GARw
Precession
Cef Pearson
Sagnac Effect
Sagnac Effect
 Use the Adi Shamir paper
Ring Laser Gyroscope
Ring Laser Gyroscope
 Talk about how Ring Laser Gyroscope works
 Problems
 Mode Lock
 The beat frequency is to small and now we can’t measure the beat
frequency.
 Sensitivity of device
 No moving system
 10degrees/hour
 Rotating system
 10^-2 degrees/hour
 The best
 10^-6 degrees/hours
 “This is sensitivity is so great that it is enough to observe the daily effect of
the moon of the earth’s rotation axis.” Adi Shamir
Ring Laser Gyroscope
Interferometric Fiber Optic Gyro
 http://www.youtube.com/watch?v=RvV2FAMHI5Q&feature=related
Interferometric Fiber Optic Gyro
Interferometric Fiber Optic Gyro
 Pros
 Longer fiber means a larger measurable phase change
 Cons
 Longer fiber means more loss from the fiber
 Thermal Fluctuations
 Change in propagation delay caused by heat
 Optical Kerr Effect
 Change in reflective index caused by intensity of light
Bibliography
 Shamir, Adi, An overview of Optical Gyroscopes
Theory, Practical Aspects, Applications and Future
Trends, May 16, 2006
 Terry Pearson, How a gyroscope works, Febuary 1997,
www.gyros.freeserve.co.uk