利用偏振成像在复杂现场快速识别金属碎屑（特约）

爆炸犯罪杀伤群众，破坏公私财产，对公共安全造成危害。为快速侦破爆破案件，需要在爆炸现场众多残留物中识别金属，找出爆炸装置碎屑。针对在复杂背景中快速识别金属碎屑的需求，提出了一种基于线偏振成像增强金属对比的方法。基于偏振光成像的原理，搭建了两种多波长偏振图像采集装置。针对多种非金属和金属材料进行实验，发现调整入射光的线偏振角度和入射角，多波长偏振成像方法在复杂现场中可以对金属与非金属快速识别和分类。通过模拟研究了多波长下金属表面反射光的线偏振度和偏振角随入射角度变化的情况，给出识别不同金属的最佳角度和照明偏振光。进一步实验结果显示:多波长线偏振成像方法有区分不同种类金属的潜力。

Rapid identification of metal debris in complicated scenes by using polarization imaging(Invited)

Crimes associated to explosives always kill the lives of people, destroy the facilities, and threaten the public security. Rapid identifying the medal debris from the residuals of the explosives in criminal scenes is the key to speed up the detection of these criminal cases. Responding to these applications, in the paper,  a method was proposed based on polarization imaging to rapidly identify the medal debris from the complicated scenes. Two setups were built, which can respectively capture polarization images with multiple colors and in a simultaneous imaging manner. Experiments of the medal and non-medal debris and their mixtures show that polarization imaging can effectively identify the medal debris if the incident angle polarization, and wavelength of the illuminating light are appropriately set. Simulations based on Fresnel formula show how the polarization degrees and angles change with the incident angle, polarization, and wavelength of the illumination light. And the results suggest that polarization imaging can identify the types of the medal debris, which is proved by the additional experiments. In summary, it is indicated that polarization imaging has the potential to rapidly identify the medal debris from the complicated scenes which would help for the physical evidence in criminal detections.