Abstract: The laser with a ring cavity (ring laser) is suggested.The principle of RL measurement is the effects of Sagnac, For this serval advantages are given to RL. Working principal,the sustainable development,possible applications are intruduced . It is used as a sensor such as ring laser gyro (RLG) in inertial navigation system. It is also used to make a dynamic goniometer for different applications of precision angle measurement. A study direction of the Application is found.

Key words: Ring laser, Laser gyroscope, Dynamic goniometer