This disclosure provides methods, systems and devices that may be used to measure, calculate, and orient a device such as a drill bit in a downhole environment. To that end, disclosed are fiber optic gyroscopes, wherein the fiber optic gyroscopes comprise elliptical fiber optic cable coils in a mutually orthogonal arrangement that is tilted relative to a longitudinal axis of a supporting shaft, e.g., tube. Light travels in opposite directions within each of the elliptical fiber optic cable coils, and, subsequently, sensors detect differences in time for each light path of the light that traveled in opposite directions within each one of the elliptical fiber optic cable coils. The elliptical nature of the fiber optic cable coils minimizes the cross-sectional area of the mutually orthogonal arrangement, and thereby makes it well-suited for use in downhole environments where space is at a premium. This disclosure also may provide an inertial measurement unit.