3D detection is an important application of Lidar. A 3D range imaging Lidar system is presented in this paper. The
longitudinal resolution of 3D range imaging Lidar is poor because of the length of pulse width and gate time of ICCD,
which together determine the detected longitudinal range from a single laser pulse shot. To improve the longitudinal
resolution, power distribution received by one pixel of ICCD is analyzed, and a method is put forward. In this method,
by setting the gate time and step interval of delay time to the value of pulse width, one object will be detected in two
neighboring images, and it can be precisely located through analysis of the pixel values in the two images. The locating
precision of this method is verified by experiments, and results show that the longitudinal resolution is improved by ten
times, that is from 1.65m to about 0.15m. Meanwhile, the detection efficiency is reduced only a little.