Abstract: A laser-based refractive surgery system includes a laser source including a laser controller, wherein at least a portion of the incident beam is directed to target eye tissue of a patient. The incident beam portion produces a reflected beam after striking the eye tissue. The system includes at least one detector for detecting the reflected beam. A computer or data processor is communicably coupled to the detector and the laser controller. The computer or data processor generates a cross-correlation function using a plurality of discrete points which digitally represent a waveform representation of the reflected beam and a plurality of reference points. The reference points are preferably associated with a digital representation of the incident beam. The laser controller receives and utilizes the cross-correlation function or parameter derived therefrom, or the ablation rate, and adjusts at least one operating parameter of the laser beam in real-time during a refractive procedure.