Range accuracy of a Gated-Viewing system compared to a 3-D Flash LADAR under different turbulence conditions

While a Gated-Viewing system primarily provides the intensity values of the captured laser radiation, it is also possible to determine range information in a static scenario by the sliding gates method. In this paper, we compare this method to a time-of-flight based 3-D Flash LADAR technique in terms of range accuracy under moderate and strong turbulence conditions. The first method requires several Gated-Viewing images (several laser pulses) with stepwise increased gate delay times. For a 3-D Flash LADAR system, one laser pulse is sufficient because for each pixel the range is determined by the time-of-flight method. We have combined a Gated-Viewing camera (640 x 480 pixels) as well as a 3-D Flash LADAR camera (128 x 128 pixels) with a pulsed 1.57 mu m laser source. The maximal laser pulse energy was 67 mJ. We have conducted field measurements at different times of day. Two reflectance panels and a vehicle at a distance of 2 km were recorded. The plates were positioned diagonal to the line of sight with an angle of about 45 degrees in order to determine range accuracies. In addition, a laser scintillometer provided atmospheric turbulence strength along the propagation path.