Range detection through the atmosphere using Laguerre-Gaussian beams

For most radar or ladar systems range information is obtained from the time necessary for an electromagnetic pulse to propagate to a target and return to a receiving antenna. In contrast, we investigate a method that replaces temporal encoding of distance with spatial encoding. In particular, we use a self-referencing superposition of Laguerre-Gaussian beams to translate propagation distance into transverse rotation of cross-section of the beam intensity. We review the mathematical foundations of the technique and discuss models for simulating its performance in turbulent atmosphere. In addition, we present a simple technique to extract the rotation angle from a two-dimensional cross-section of the beam. Preliminary results indicate that the technique is robust with respect to propagation in a turbulent atmosphere.