50th anniversary of the laser gyro

This paper describes the history of a laser gyroscope, which originated from one of the fundamental physics area - optics of moving bodies, and in particular, the Sagnac effect. Background and prediction of the first ring laser gyro (RLG), which opened a new era of wave gyroscopes, is described. Its scientific basis was Einstein's theory of stimulated emission, which was expounded by the Nobel laureates N.G. Basov, A.M. Prokhorov and C. Townes that created the world's first quantum generator (maser) - the predecessor of coherent optical radiation - laser. That was enough to create the first laboratory model of the ring laser gyro in 1962. The history of the RLG construction concepts from its first samples of minimal configuration to multi-frequency Zeeman modifications with nonplanar resonators is observed. The leading role of a ring laser gyroscope in the creation of inertial measurement units, strapdown inertial and integrated navigation systems is shown. Special attention is paid to the current state of the gyro market in general and the place of RLG among them. The general trends in the inertial sensors market development are highlighted. The main producers of either RLGs or systems based on them are mentioned. Information on the development of ultra large ring laser gyroscopes is provided.