Gated viewing and high-accuracy three-dimensional laser radar

We have developed a fast and high-accuracy three-dimensional (3-D) imaging laser radar that can achieve better than 1-mm range accuracy for half a million pixels in less than 1 s. Our technique is based on range-gating segmentation. We combine the advantages of gated viewing with our new fast technique of 3-D imaging. The system uses a picosecond Q-switched Nd:Yag laser at 532 nm with a 32-kHz pulse repetition frequency (PRF), which triggers an ultrafast camera with a highly sensitive CCD with 582 x 752 pixels. The high range accuracy is achieved with narrow laser pulse widths of approximately 200 ps, a high PRF of 32 kHz, and a high-speed camera with gate times down to 200 ps and delay steps down to 100 ps. The electronics and the software also allow for gated viewing with automatic gain control versus range, whereby foreground backscatter can be suppressed. We describe our technique for the rapid production of high-accuracy 3-D images, derive performance characteristics, and outline future improvements.