Fiber optic north finder is one kind of north finder. The north finder is actually an inertial system. The north finder is composed of an IMU and a north finder algorithm, and the IMU is composed of a gyroscope sensor and an accelerometer sensor. Therefore, the gyro sensor inside the fiber optic north finder is a fiber optic gyroscope.
Fiber optic north finder can be used in gyro tools and logging tools, as well as in mining, mapping and other fields. It has a north finding accuracy of 1-0.25°.

More about Fiber optic North Finder: https://www.ericcointernational.com/north-finders/fiber-optic-gyro-north-finder/er-fiber-optic-gyro-north-finder-for-mining.html