Educational Objectives
l He-Ne Ring Laser
l Ring Laser Modes
l Interference
l Single Mode Etalon
l Sagnac Effect
l Mode Lock-in
l Measurement of Rotation
l Dynamic Range
This active laser gyroscope contains a ring laser consisting of an openframe He- Ne tube and a triangular resonator. The whole ring laser is set up ona motorized rotational platform. The rotational velocity can be varied allowingto the dynamic range of the Gyroscope to be investigated. Counter-rotatingmodes of the ring laser are coupled out and are superimposed for demonstrationand measurement of the Sagnac effect. The resulting interference is detectedand electronically converted to a frequency proportional to the rotational velocity.The lock-in threshold is determined by variation of the rotation frequency. Singlemode operation is achieved by an etalon mounted in the ring resonator.