Enhanced hybrid lidar-radar ranging technique

A new hybrid lidar-radar underwater ranging technique is presented to enhance optical ranging in underwater environments. This technique has the potential to extend the unambiguous range by an order of magnitude while maintaining range precision that is comparable to existing techniques. The technique combines frequency domain reflectometry (FDR) [1] and modulated continuous wave (CW) ranging [2] to simultaneously achieve good unambiguous range and range precision performance. Theory and simulation are presented to demonstrate the FDR and combined FDR/CW approach. These results indicate that for the system parameters chosen the combined FDR/CW approach can extend the unambiguous range from tens of centimeters to approximately ten meters depending on water turbidity while maintaining the range precision associated with the CW approach.