Studies On One-dimensional Scanning Laser Active Imaging

As a kind of modern optical remote sensing equipment, LIDAR has been widely used in many aeras, like military, civilian application, meteorology, etc. Most of the developed forward-looking-automobile-LIDAR-system is with two-dimansional scanning technology, which is more complex and with lower imaging speed, comparing with one-dimensional scanning system. In this thesis, a one-dimensional scanning active imaging LIDAR system used for automobile obstacle-avoidance was researched, which is compact and simple, low-cost, and fast imaging.In this thesis, the principles of scanning imaging lidar, and the design of one-dimensional scanning laser active imaging system based on these principles were introduced at first. A cylindrical lens system for 905nm laser diode collimation and Kepler variable beam delivery system were designed with ZEMAX optical design software. The beam could meet the requirement of experiment after being simulated and researched in the same software. According to optical system structure, the best detector-position was theoretically calculated and simulated, and then studied experimentally by He-Ne laser. In addition, the imaging of the infinity and near targets were calculated and analyzed, and the effective imaging range of near target was studied experimentally.Signal processing systems of one-dimensional scanning laser active imaging system were introduced, including the occurrence of the signal, acquisition, and real-time display of lidar imaging. Drive signal for scanning system, trigger signal for laser, and synchronization signal were generated by HY-8110 arbitrary signal generating card. Optical signal was detected by APD model C30659-900 and transmitted into an amplifier based on AD603 which with tunable gain range of 0~34dB, then Analog-To-Digital converted by the F508B signal high-speed data acquisition card. The real-time displaying system including user-controlling interface and a real-time displaying window was programmed in VC++ environment. The synchronization of arbitrary signal generator and data acquisition card was studied and an effective solution was given.Both of indoor-imaging and outdoor-imaging were studied. The indoor experiments got a nice imaging, while the targets were located at two positions as far as 9m and 16m, respectively. As to outdoor research with detective distance more than 60m, using a new developed range-gated method, clear intensity image of one-dimensional scanning lidar system was achieved. At last, a high-resolution imaging map was obtained in study on improvement of the image quality, using spectral filtering method to improve SNR.