Abstract: Equipment and techniques for the accurate estimates of the turbulence profile to improve the performance of adaptive optics systems designed to compensate the degradation effects of turbulence on directed energy systems, in astronomy, and in laser communication systems. The present invention is an optical turbulence profiler. The invention includes a cross-path LIDAR. The cross-path LIDAR technique uses laser guide star technology combined with a cross-path wavefront sensing method. In this method, two Rayleigh, or sodium, laser beacons separated at some angular distance are created by using a pulsed laser and a range-gated receiver. In preferred embodiments a Hartmann wavefront sensor measures the wavefront slopes from two laser guide stars. The cross-correlation coefficients of the wavefront slope are calculated, and the turbulence profile of refractive index structure characteristic Cn2(z) is reconstructed from the measured slope cross-correlations.