How does ring laser gyro works?

A ring laser gyro (RLG) operates based on the principles of laser interference and Sagnac effect. It consists of two counter-propagating laser beams traveling around a closed loop. When the gyro rotates, the path length for one beam increases while the other decreases, resulting in a phase difference between the two beams. This phase difference is detected as a frequency shift, which is proportional to the rate of rotation, allowing for precise measurements of angular velocity.