Study On Target Reflective Characteristics Of Pulsed Laser Proximity Detection

Pulse laser for target detection and recognition is the key point to be solved urgently in laser short range detection technology, and the backscattering characteristic of the target is important for the damage precision and efficiency of the short range detection. The roughness and deposition of target surface have great influence on echo signal.In this thesis, backscattering characteristics of the targets with various surface roughness have been studied.Backscattering characteristic of the target surface is described by the received power equation. Effects of parameters, such as background radiation power, transmission coefficients of optical elements and atmosphere, to the backscattering characteristic of the target have been discussed. Fundamental features and their generating methods of the surfaces with various roughness, influencing on the backscattering characteristic, have been analyzed. Surface roughness model has been built and optic simulation of the surface roughness has been performed with Tracepro. With the analysis of the influence of the target surface roughness on backscattering characteristic, the received power equation has been revised, to provide reference for reflection characteristics experiment.Then, laser short range detection transmitting and receiving modules have been designed and manufactured. A platform for the measuring of the receiving power of the laser backscattered from the target with various roughness has been built to verify the model. The changes of echo signal were studied under different surface roughness, distance and angle. Through experiment data analysis, the way of selecting revised echo power equation coefficient has been gained. And it has a guiding significance to backward signal processing.Finally, the influence of surface sediment on target backscattering characteristic experiment has been designed. The result indicates that rainfall deposition has strong influence on the target surface which has low water absorption coefficient; for the dust deposition, backscattering characteristic is influenced by surface roughness and the depth of the deposition. When the depth is larger than the roughness, the deposition and its topography determine backscattering characteristic.The theoretical model and experimental result provide reference for laser short range detection research and laser ranging accuracy improvement of laser fuse.