Definition of ring laser in English:

ring laser

noun

Physics
  • A laser in which two beams are made to travel in opposite directions around a closed path by means of mirrors, typically used in aircraft, missiles, etc., in order to detect rotation; frequently attributive, as "ring laser gyroscope", etc.; (also) any of various other lasers in which the light is made to travel around a ring.

    A typical ring laser acts as an interferometer: any rotation of the device will create a phase difference between the two beams, which manifests as an interference pattern when they are recombined.

Origin

1960s.