Question id 181 - Aircraft General Knowledge - Instrumentation - ATPL - Airline Transport Pilot license

A gyroscope associated with a laser compensating for gimballing errors.
A gyroscope associated with a laser compensating for apparent wander due to the rotation of the earth.
Two rotating cavities provided with mirrors.
Frequency difference between two laser beams rotating in opposite direction.

Training tests and timed exam simulations ATPL - Airline Transport Pilot license