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Range-gated laser imaging technology was proposed in 1966 by LF Gillespiethe in U.S. Army Night Vision Laboratory(NVL). Using pulse laser and intensified charge-coupled device(ICCD) as light source and detector respectively, range-gated laser imaging technology can realize space-slice imaging while restraining the atmospheric backs-catter, and in turn detect the target effectively, by controlling the delay between the laser pulse and strobe. Owing to the constraints of the development of key components such as narrow pulse laser and gated imaging devices, the research has been progressed slowly in the next few decades. Until the beginning of this century, as the hardware technology continues to mature, this technology has developed rapidly in fields such as night vision, underwater imaging, biomedical imaging, three-dimensional imaging, especially range-gated three-dimensional(3-D) laser imaging field purposing of access to target spatial information. 3-D reconstruction is the processing of restoration of 3-D objects visible surface geometric structure from three-dimensional(2-D) image. Range-gated laser imaging technology can achieve gated imaging of slice space to form a slice image, and in turn provide the distance information corresponding to the slice image. But to inverse the information of 3-D space, we need to obtain the imaging visual field of system, that is, the focal length of the system. Then based on the distance information of the space slice, the spatial information of each unit space corresponding to each pixel can be inversed. Camera calibration is an indispensable step in 3-D reconstruction, including analysis of the internal structure of camera parameters and the external parameters . In order to meet the technical requirements of the range-gated 3-D imaging, this paper intends to study the calibration of the zoom lens system. After summarizing the camera calibration technique comprehensively, a classic calibration method based on line is selected. One-to-one correspondence between visual filed and focal length of system is obtained and offers effective visual field information for the matching of imaging filed and illumination filed in range-gated 3-D imaging technology. On the basis of the experimental results, combined with the depth of field theory, the application of camera calibration in range-gated 3-D imaging technology is futher studied.
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