Ring laser gyroscope

It operates on the principle of the Sagnac effect which shifts the nulls of the internal standing wave pattern in response to angular rotation.

Many tens of thousands of RLGs are operating in inertial navigation systems and have established high accuracy, with better than 0.01°/hour bias uncertainty, and mean time between failures in excess of 60,000 hours.

The advantage of using an RLG is that there are no moving parts (apart from the dither motor assembly (see further description below), and laser-lock), compared to the conventional spinning gyroscope.

Additionally, the entire unit is compact, lightweight and highly durable, making it suitable for use in mobile systems such as aircraft, missiles, and satellites.

Contemporary applications of the ring laser gyroscope include an embedded GPS capability to further enhance accuracy of RLG inertial navigation systems on military aircraft, commercial airliners, ships, and spacecraft.

"Ring laser gyroscopes (RLG) have demonstrated to currently be the most sensitive device for testing rotational motion with respect to an inertial frame.

This is less sensitive in a single traverse of the ring than the RLG, in which the externally observed phase shift is proportional to the accumulated rotation itself, not its derivative.