Effect of spatial polarization characteristics of analyzer on high-precision waveplate calibration

Waveplates are widely used in solar physics for polarization measurements in solar telescopes. Accurate calibration of the fast-axis azimuth and retardance of waveplates is crucial for improving the precision of these measurements. In this paper, we suggest that the spatial polarization characteristics of the analyzer in waveplate calibration system, using the intensity method, can introduce errors in calibrating the fast-axis and retardance. Therefore, we propose a correction method that introduces an analyzer model during the waveplate calibration process to address these errors. Numerical simulations demonstrated that the impact of these characteristics of the analyzer on the waveplate calibration depends on the form of these characteristics and the parameters of the waveplate itself, leading to calibration errors over 0.1° in fast-axis orientation and 1° in retardance in some cases. We conducted simulations using a calibration system as an example. The simulations indicate that, in certain cases, the correction method can reduce these errors significantly: from-0.27°to-0.08° for fast-axis orientation and from -3.8° to -0.01° for retardance. This method effectively reduces calibration errors of waveplate parameters induced by the spatial polarization characteristics of the analyzer in intensity-based methods.