High performance ring laser gyroscope with magneto-optical bias

Claim 1

A ring laser rotational rate sensor having a differential bias system to prevent low angular rate lock-in, comprising: a first laser cavity forming a closed loop path containing a lasing medium in said closed loop path for producing a first pair of counter-rotating light beams in said path, a second laser cavity located in the plane described by said first laser cavity forming a second closed loop path containing a second lasing medium in said second closed loop path for producing a second pair of counter-rotating light beams in said path with at least one light beam of each of said first and second closed loop paths being substantially parallel and separated by short distance, means for producing magNeto-optical rotation of light beams disposed to have said parallel light beams pass therethrough, and first and second photodetector and retroreflector means receiving respectively said first and second laser cavity light beam pair for producing outputs corresponding respectively to frequency differences between said first and second pair of counter-rotating light beams, said outputs indicating angular rotation of said first and second laser cavities about an axis perpendicular to said plane.