Optimized spatially modulated polarimetry with an efficient calibration method and hybrid gradient descent...

High accuracy and fast polarization measurements at a low light field are significant in various applications, spanning from quantum optics to diagnosis of living biological tissue. In this paper, we developed an optimized spatially modulated polarimetry (OSMP) with an efficient calibration method that establishes a quantitative link between the intensity distribution of an arbitrary incident polarization state and four intensity distributions of specific input polarization states. Such a calibration method not only considers the total polarimetric errors induced by polarization elements and the focusing lens but also simplifies the procedure of calibration. A hybrid gradient descent (HGD) algorithm, combining the rapidity of optimization of gradient descent (GD) algorithm and the accuracy of optimization of direct enumeration (DE) algorithm, was proposed to restructure the Stokes parameters. Experiment results illustrate that the proposed method can significantly improve the speed and accuracy of polarization measurements over existing spatially modulated polarimeters based on the vortex wave retarder, whether in strong or low light fields.