Proceedings Article | 29 August 2009
Xue-chun Tan, Guang-yong Jin, Zhi-chao Wu, Ming Ling, Zhu Liang
KEYWORDS: LIDAR, Receivers, Transmitters, Pulsed laser operation, Imaging devices, Signal processing, Avalanche photodetectors, Semiconductor lasers, Distance measurement, Sensors
The development of range-imaging devices is motivated by various ground and space applications. Tasks in space
missions include docking, rendezvous, manipulating robotic arms, landing and autonomous rover applications, sample
identification and surface mapping. The ground applications include the guidance of vehicles, robotic and manipulator
arms, and other autonomous or teleoperated machines, as well as surface or construction model generation. Without the
scanner devices, scannerless imaging lidars have the characteristic of high frame rate, wide field of view and high
reliability,which can be successful used in terminal guidance. Diode pumped laser radar with high repetition rate is
studied in this paper. A bistatic system is set up and a high speed signal processor for the system is researched. In a
conceptual sense, the imaging lidar has two parts, a transmitter and a receiver. Their field of views overlap throughout
the measuring range.The imaging lidar operates as follows. Based on principle of pulsed time-of-flight (TOF) laser range
finding, the solid-state laser diode-pumped laser produces short laser pulses, which though the expanded lens, then
reach the target. The back reflected light is collected with a receiver lens and fed through optical fibres to discrete
avalanche photo diodes (APDs). When a received pulse is detected by the comparator a time to digital converter (TDC)
stops counting and a time interval, corresponding to the range, is produced. The precision of a single measurement is
about ±4.0cm, but better precision is achieved by averaging. Information about the reflectivity of the target is gathered
by recording the amplitude of the received pulse. Range images with the lidar prototype were taken indoors, the
measuring distance was about 14m.
