ABSTRACT
The gyroscope, another big achievement of photonics science, is an inertial sensor measuring the angular rotation of a mobile vehicle respect to the inertial frame of fixed stars. It is the heart of modern INU (inertial navigation unit) assisting the flight of all newly built airliners. It is based on the measurement of the Sagnac phase-shift due to rotation, read by an internal or external interferometer. After deriving the small Sagnac phase-shift signal, the quantum limit of measurement is assessed and performance of minimum rotation rate is evaluated. Basic configurations of gyroscope are then scrutinized, and working configurations for both the RLG (ring laser gyro) and FOG (fiber optics gyro) are developed in details, with the discussion of a number of minute effects disturbing the ultimate performance, like for example the Shupe effect that has recently led the FOG to reach the inertial grade performance. Detailed analysis and design principles for choosing the components of RLG and FOG are presented. Last, the chapter considers variants to the basic scheme of FOG, like the integrated-chip, the resonant ring FOG, the 3x3 minimum part-count FOG, and also compares the photonic gyro to the MEMS gyro, an emerging technology for low-grade, low cost consumer and automotive applications.
