Revealing molecular structure of starch with Stokes-vector based second harmonic generation microscopy

We report on the measurement and characterization of polarization properties of second harmonic (SH) light from starch granule using a Stokes vector based microscopy. The four-element Stokes parameters are the most complete description of the polarization state of SH light, including any depolarization effects. Various polarization parameters, such as the degree of polarization, the degree of linear polarization, the degree of circular polarization, as well as anisotropy are extracted by implementing a pixel by pixel image analysis from the 2D reconstructed SH Stokes images of starch granule. Furthermore, we implemented the technique by varying the polarization states of excitation light and recording the resulting Stokes parameters at micro-meter depths of resolution in order to investigate the molecular structure and orientation of the samples.