Abstract: A ring laser gyro having a cavity with at least one transducer-actuated mirror is controlled to conform to a preselected model of cavity operation. Control is accomplished by sampling cavity data, comparing the data to the model to generate an error signal, and controlling the mirror according to the error signal. In a preferred embodiment, at least two mirrors are dithered and the model defines an optimal amplitude of mirror dither at which theoretical lock-in error is zero. In another preferred embodiment, the sampled data corresponds to laser intensity within the cavity and the model defines an optimal intensity displaced from the maximum within an operating mode of the cavity. The model may define a plurality of operating modes of the cavity, ranked according to gyro performance for different values of a preselected environmental condition. The environmental condition is then sensed on an ongoing basis and used to select an optimal mode.