| In the case that the illumination environment is extremely weak,the detection capability of the optoelectronic device to the target is greatly limited by factors such as aperture,spatial and temporal,resulting in a decrease in the contrast between the target and the background,and the degradation of the imaging quality,which make it difficult to perform the detection and detection task.Polarization imaging technology can detect the polarization information of the target without being affected by the light intensity.Therefore,the combination of polarization imaging technology and low-light imaging technology can greatly improve the target observation ability in the weak light environment.The traditional time-sharing polarization imaging system cannot collect information on motion scenes,and it is easy to introduce additional errors and false information to imaging system.In order to obtain all the polarization information of the dynamic scene at the same time,the real-time imaging system came into being,solving the problems of the time-sharing system.By studying the Stokes polarization imaging method,the current common polarization imaging systems are analyzed and compared.Based on the principle of polarization imaging,and combined with aperture segmentation technology,a micro-light polarization real-time imaging optical system is designed.The optical system adopts a common-aperture four-channel array structure,and divides the four polarization states to be measured into four independent imaging channels.The sub-aperture imaging lens group performs four-quadrant segmentation imaging on the detector target surface.Each polarization channel acquires an intensity image of a different polarization state of the target by placing polarizing plates having different polarization states,thereby realizing real-time polarization imaging.The system can realize real-time polarization imaging in the lowest illumination 1×10-3lx environment.The system finally achieves a focal length of 100mm,an overall F number of 1.2,a working waveband of 0.4 to 0.85?m,and a system single channel image height of 14mm.After the overall optimization of the system,the MTF value of the optical system is higher than 0.57 at 40 lp/mm,and the RMS size of the spot is smaller than the size of a single pixel,which satisfies the calculation index.At the same time,this paper uses the micro-light EMCCD and micro-ray grating polarization to build a time-sharing micro-light polarization imaging system.The time-sharing polarization imaging system is built in the outdoor starlight environment to carry out polarization imaging experiments on the target scene,and the experimental verification of the feasibility of micro-light polarization imaging is completed.The experimental results show that the target background contrast of different kinds of artificial targets is improved to different extents.In the micro-light night vision imaging,the polarization degree image is higher than the intensity image,the average gray value of the image is increased by 13% and the information entropy is increased by 7.9% relative to the intensity image.Therefore,the micro-light polarization imaging method can improve the artificial target and the natural background contrast,which is more efficient than simply using the intensity imaging to identify the target. |
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