Abstract: A resonator feedback system is disclosed wherein the output from a resonator having adaptive optics is monitored by a detector within a feedback loop to provide electrical control signals to actuators attached to the adaptive optics to control the phase of the radiation within the resonator to produce an output beam having a near diffraction limited distribution. In one embodiment, a portion of the output beam is phase modulated at discrete frequencies and focused through an aperture onto a detector. Far field amplitude fluctuations at the focal point resulting from phase perturbations of the radiation within the resonator produces an amplitude varying electrical input signal which is synchronously detected with multidither signals utilized to impress the phase modulation to produce multicorrection signals.