Calibration and data extraction in a Stokes polarimeter employing three wavelengths simultaneously

Area of Science:

• Optical Engineering
• Metrology

Background:

• Stokes polarimetry is crucial for characterizing light polarization.
• Simultaneous multi-wavelength measurements require robust calibration techniques.
• Liquid crystal variable retarders (LCVRs) and Glan-Thompson polarizers are key components.

Purpose of the Study:

• To present a novel calibration and data extraction method for a three-wavelength Stokes polarimeter.
• To enable simultaneous measurement and calibration across multiple wavelengths.
• To evaluate the performance enhancement achieved by the proposed fitting calibration procedure.

Main Methods:

• Utilized two LCVRs and a Glan-Thompson linear polarizer for the Stokes polarimeter.
• Employed a recently developed fitting calibration procedure with consistent samples and voltages for all wavelengths.
• Generated four and six known calibration beams using polarizers and wave plates (half-wave and quarter-wave) at 632 nm.

Main Results:

• The fitting calibration procedure demonstrated good agreement with expected results.
• An approximate 50% reduction in total Root Mean Square (RMS) error was achieved using four calibration samples.
• Using six calibration samples yielded a negligible additional error reduction compared to four samples.

Conclusions:

• The proposed fitting calibration method is effective for simultaneous multi-wavelength Stokes polarimetry.
• The method significantly improves accuracy, particularly with an optimized number of calibration samples.
• The approach offers a practical solution for enhancing polarimeter performance.