偏光片细微外观缺陷偏振成像检测方法

针对偏光片细微外观缺陷难以成像、难以检测的问题，该文提出一种基于偏振成像的外观缺陷检测新方法。通过缺陷偏振态指标测量结果，定性描述了对比度增强机理。利用缺陷与正常区域之间透射光偏振态的显著差异，大幅提高缺陷的成像对比度，从而简化后续图像处理算法，提高检测速度和准确率。实验结果表明，偏光片外观缺陷平均检出率达到97.3%，平均单个样品检测时间约为0.22 s，基本满足产业化应用要求。

Inspection of Slight Aesthetic Defects in a Polarizing Film via Polarization Imaging

The slight aesthetic defects of polarizing films can hardly image and are difficult to detect. A novel method of detecting the slight defects based on polarization imaging is proposed in this paper. The mechanism of contrast enhancement is described qualitatively through the measurement results of defect polarization index. The image contrast of the defect is greatly improved by making use of the significant difference of polarization state of the transmitted light between the defect and the normal region, so as to simplify the following image processing algorithm and improve both the detection speed and accuracy. The experimental results show that the average recognition rate of polarizer aesthetic defects is 97.3%, and the average detection time of a single defect sample is about 0.22 s, thus it meets basically the requirements of industrial application.