An optical beam tracking system comprising signal processing hardware configured: to receive axis signals (520, 530, 540, 550) from a multi-axis position sensing detector, each axis signal (520, 530, 540, 550) indicative of a beam position of an optical beam incident on the multi-axis position sensing detector, each axis signal (520, 530, 540, 550) corresponding to an axis of the multi-axis position sensing detector; to generate a reference signal by summing the axis signals (520, 530, 540, 550); for each axis of the multi-axis position sensing detector: to convert a phase of a first axis signal (520, 540) of the axis to have a 90 degree phase difference from a second axis signal (530, 550) of the axis; to generate an axis-phasor signal (640, 650) by summing the first and second axis signals (520, 530, 540, 550), the axis-phasor signal (640, 650) having an angle that maps to the beam position of the optical beam; and to compare the axis-phasor signal (640, 650) and the reference signal to determine a phase difference, the reference signal based on the axis signals, the phase difference mapping to a beam position error (780, 790) along the corresponding axis on the multi-axis position sensing detector; and to determine a mirror position of a mirror directing the optical beam based on the beam position error (780, 790) of at least one axis of the multi-axis position sensing detector. to receive axis signals (520, 530, 540, 550) from a multi-axis position sensing detector, each axis signal (520, 530, 540, 550) indicative of a beam position of an optical beam incident on the multi-axis position sensing detector, each axis signal (520, 530, 540, 550) corresponding to an axis of the multi-axis position sensing detector; to generate a reference signal by summing the axis signals (520, 530, 540, 550); for each axis of the multi-axis position sensing detector: to convert a phase of a first axis signal (520, 540) of the axis to have a 90 degree phase difference from a second axis signal (530, 550) of the axis; to generate an axis-phasor signal (640, 650) by summing the first and second axis signals (520, 530, 540, 550), the axis-phasor signal (640, 650) having an angle that maps to the beam position of the optical beam; and to compare the axis-phasor signal (640, 650) and the reference signal to determine a phase difference, the reference signal based on the axis signals, the phase difference mapping to a beam position error (780, 790) along the corresponding axis on the multi-axis position sensing detector; and to convert a phase of a first axis signal (520, 540) of the axis to have a 90 degree phase difference from a second axis signal (530, 550) of the axis; to generate an axis-phasor signal (640, 650) by summing the first and second axis signals (520, 530, 540, 550), the axis-phasor signal (640, 650) having an angle that maps to the beam position of the optical beam; and to compare the axis-phasor signal (640, 650) and the reference signal to determine a phase difference, the reference signal based on the axis signals, the phase difference mapping to a beam position error (780, 790) along the corresponding axis on the multi-axis position sensing detector; and to determine a mirror position of a mirror directing the optical beam based on the beam position error (780, 790) of at least one axis of the multi-axis position sensing detector.