Draw a diagram of a minimum-configuration fibre interferometer gyroscope. Label the system components and briefly describe, with reasons, the desirable features and main function of each component in the system. For a fibre gyroscope consisting of a circular coil of N turns of fibre, derive a formula expressing the optical phase shift ?φ produced by a rotation rate Ω in terms of the coil area A and source wavelength λ0. Use your formula to calculate the unambiguous range of rotation rate measurable by a gyroscope employing an 830 nm source and 700 m of fibre wound on to a coil of 10 cm diameter. How could this range be extended?