A common aperture active imaging system

In this paper, the researches and experiments on the feasibility of a common aperture active imaging system using a polarization beam splitter have been presented. The system includes a CCD imaging unit, a semiconductor laser unit, a polarization beam splitter, a linear polarizer, a quarter-wave plate, a telescope objective, a designed laser collimating lens and mechanical assembling structures. According to the analysis with Jones matrix, the system gains remarkably high utilization ratio of luminous energy. Also, the system can reach an illuminating distance of 3km, a laser divergence angle of 0.504° and a degree of uniformity of 83% theoretically. The experiments have been conducted to obtain images of objects at 300m and 3km. From the results, clear illuminated objects can be identified and no impacts of back scattering of atmosphere turbulence have been detected. However, to make this kind of systems more effective, higher demands on the extinction ratio, reflectivity and transmissivity of the polarized components and the uniformity of the illuminating spot should be met.