This resonator supports a number of resonant modes. Since this phase shift is detected by an interferometric technique, these FOGs are called interferometric FOGs (IFOGs).Īn optical fiber can be used to realize a passive optical ring resonator. The most diffused FOGs are phase-sensitive where angular rate is estimated by measuring the rotation-induced phase shift between two beams that counter-propagate in a fiber coil. High performance gyros market is actually dominated by He–Ne RLG which is widely employed for aircraft navigation but FOG has been effectively applied for inertial navigation of submarines and spacecrafts which move in a more quiet environment. Typically FOGs are not used for aircraft navigation because this application requires a high immunity to external perturbations. Recently a FOG-based IMU has been used for inertial navigation of rovers vehicles developed by NASA for Mars exploration. For example, a FOG exhibiting bias drift around 0.001 °/h has been used in the Pleiades satellites for Earth Observation.
![fiber optic gyroscope fiber optic gyroscope](https://www.neubrex.com/img/applications/gyro/gyro0/001_a.jpg)
FOGs have been used in applications requiring medium and low performance such as robotics and automotive, but also in space applications, which require high or very high resolution. For example, bias drift typically ranges from 10 to 0.0002 °/h.
![fiber optic gyroscope fiber optic gyroscope](https://www.unmannedsystemstechnology.com/wp-content/uploads/2020/01/fiber-optic-gyro-vg1703spe-e1611570651578-300x177.jpg)
Despite a considerable research amount during the last decades, FOG has not yet superseded the He–Ne RLG because of the large existing RLG-based industrial infrastructure and the FOG higher sensitivity to external perturbations (temperature changes, vibrations and so on).įOG performance can be very high, but also medium and low, depending on the used fiber and on the accuracy of the read-out optoelectronic system. The exploitation of optical fibers to realize an optical angular rate sensor was investigated with the hope of reducing cost, simplifying the fabrication process and increasing accuracy with respect to the He–Ne RLG. In the late 1960s, the development of the fiber optic gyroscope (FOG) was started at US Naval Research Laboratories, Washington (USA) (Brown RB, NRL Memorandum Report N1871, 1968).