Stress measurement and error correction based on pixelated polarization camera

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.