一种基于偏振相机的应力测量方法及其误差校正

Stress measurement and error correction based on pixelated polarization camera

  • 摘要: 基于Muller矩阵和 Stokes矢量测量原理,提出了一种利用圆偏振光、无旋转元件的应力测量和在线误差校正方法。该方法通过偏振相机获取的光强信息计算出待测样品的相位延迟,对相位延迟进行溯源便可得到样品的应力分布。通过分析标准1/4波片的相位延迟和偏振相机消光比对测量结果的影响,提出了相应的在线测量与校正方法。为验证方案的可行性,搭建了一套应力测量系统,利用该系统测量了一块经计量部门赋值的633 nm波长的1/4波片,并用提出的误差校正方法校正了测量结果。结果表明:校正前后波片相位延迟相对误差分别为11.5%和1.73%,校正后的相对误差主要由线偏振器产生。所提方法具有测量过程简单,精确度高等特点。

     

    Abstract: Based on the Muller matrix and Stokes vector measurement principles, this paper proposes a stress measurement and online error correction method using circularly polarized light and no rotating elements. The polarization camera captures the intensity information of the transmitted light to calculate the phase retardance of the specimen under test. By tracing back the phase retardance, the stress distribution of the specimen can be obtained. We analyzed the effects of the phase retardance of a standard 1/4 waveplate and the extinction ratio of a polarization camera on measurement results, and proposed corresponding online measurement and calibration methods. To validate the feasibility of the proposed approach, a stress measurement system was set up. This system was utilized to measure a 1/4 waveplate with a wavelength of 633 nm that had been calibrated by the metrology department. The measurement results were then corrected by using the error correction method described in the paper. The results indicated that the relative errors of the waveplate phase retardance before and after correction were 11.5% and 1.73%, respectively. The post-correction relative error was primarily caused by the linear polarizer. The proposed method exhibits characteristics such as simplicity in the measurement process and high accuracy.

     

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