A fiber optic gyroscope is an instrument that accurately determines the orientation of a moving object. When the beam advances in an annular passage, if the annular passage itself has a rotational speed, then the time required for the light to advance in the direction of the passage of the passage is greater than the time required to advance in the opposite direction of the rotation of the passage. That is to say, when the optical loop rotates, the optical path of the optical loop changes with respect to the optical path of the loop at rest in different forward directions. By using this change in optical path, if the speed of the loop is measured by interfering with the light traveling in different directions, an interference fiber gyro can be manufactured, if the change of the optical path of the loop is utilized Resonant fiber optic gyroscopes can be fabricated by interfering with the light that circulates continuously in the loop, that is, by adjusting the resonant frequency of the light in the fiber loop and measuring the rotational speed of the loop.
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