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摘要:红外偏振成像可突显目标、识别真伪,准确掌握目标红外辐射偏振特性可有效提高目标的探测识别概率。针对现有目标红外辐射偏振特性模型未考虑粗糙表面导致的遮蔽效应的问题,本文基于微面元双向反射分布函数模型,利用穆勒矩阵构建出含有遮蔽函数的粗糙表面红外辐射偏振度的斯托克斯解析模型。针对光线表面粗糙度和入射角对金属和非金属目标红外辐射偏振度的影响进行定量分析。分析结果表明:无论是金属还是非金属,其红外自发辐射偏振度都随粗糙度的增大而减小,非金属自发辐射偏振度下降的幅度大于金属偏振度;当粗糙度及温度相同时,金属的红外辐射偏振度始终大于非金属;红外辐射偏振度先随入射角的增加而增加,而后在特定入射角下达到峰值,超过一定入射角后,偏振度大幅下降,金属和非金属的红外辐射偏振度间的差异在一定入射角度范围内将达到最大,这有助于区分金属与非金属。最后,利用长波红外微偏振成像系统和近红外偏振成像系统进行不同场景目标的图像采集,获取目标的红外辐射偏振特性,实验结果与理论分析结果基本吻合。本文对研究目标偏振特性、优化设计红外偏振系统以及后续偏振图像处理均具有重要意义。Abstract:Infrared polarization imaging is advantageous for its ability to enhance image contrast and identify true-false targets. In order to improve detection and identification probability, it is necessary to accurately obtain the infrared radiation polarization properties of the targets. However, the traditional analytical model of infrared radiation polarization ignores the shadowing effect caused by rough surfaces. Based on the surface microelement bidirectional reflectance distribution function and by using a Muller matrix, the stocks analytical model of the infrared radiation polarization degree of the rough surface is constructed with a shadowing function. The effects of the incident angle and the surface roughness on the polarization of the metallic and nonmetallic targets are analyzed quantitatively. The analysis results show that the polarization degree of infrared spontaneous radiation decreases with an increase in the roughness of both the metal and the nonmetal, and the decrease of polarization degree of nonmetallic is greater than that of metal. Under the same roughness and temperature, the degree of polarization of the infrared radiation of the metal is always greater than that of the nonmetal. The polarization degree of infrared radiation firstly increases with the incident angle, and reaches a peak value within a specific range of incident angle, and then decreases dramatically. The difference in the degree of polarization between the metallic and nonmetallic infrared radiation reaches a maximum within a certain range of incident angle. This property is useful for distinguishing the metal and nonmetal. Finally, a long-wave infrared micro-polarization imaging system and near-infrared polarization imaging system are used to collect different images. The infrared radiation polarization properties of the targets are reasonably consistent with the results of the theoretical analysis. This research is of great significance for analyzing the polarization properties of real targets, designing infrared polarization systems and processing polarization images.
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表 1成像系统主要技术参数
Table 1.Main technical parameters of the imaging system
Long-wave infrared
micro-polarization cameraNear infrared detector Wavelength/μm 8~12 0.9~1.7 Focal length/mm 60 50 F 1 1.4 Pixel number 640×512 640×512 Pixel size/μm 17 15 -
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