Fiber optic gyro information

This is an animation of the anti-nodes of a fiber-optic gyroscope which has the following characteristics:

1. Driven by a monochromatic light source.
2. The round trip optical loss is near zero,
3. It is operated open loop.

The reason for the first characteristic is that, with a broadband source, the only anti-nodes that would be visible are those near the longitudinal center of the fiber coil and that would make the animation dynamics unclear.

The reason for the second characteristic is that, even with a monochromatic source, the anti-nodes near the detector would be very low contrast and it would be difficult to see their motion with respect to the detector.

The reason for the third characteristic is that, operated closed-loop, the anti-nodes near the detector and at the opposite diameter of the coil would not move at all and there would be no animation to see.

For a given input rate and with a circular coil of radius a, the number of anti-nodes displaced, N, is given by the simple expression:

where L is the total length of the fiber, l is the wavelength of the source, c is the speed of light in vacuum, and W is the rotation rate expressed in radians per second.

The reader is expected to make the obvious conclusion that the rotation rate can be discerned by the decimal number of anti-nodes that the detector senses as they move relative to it.