An Investigation of the Polarization States of Light Reflected from Scarab Beetles of the Chrysina Genus

Abstract: The polarization behaviour for six species of Scarab beetles from the Chrysina genus is investigated with Mueller Matrix Spectroscopic Ellipsometer (MMSE). The m41 element of the matrix, which is related to the circular polarization behaviour, is analysed. The ellipticity, degree of polarization and azimuth angle are also presented to get a better understanding of the polarization effect. The measurements were done with a dual rotating compensator ellipsometer. The measured wavelength region was from 240 to 1000 nm and the angle of incidence from 25° to 75° in most of the cases. In general very high ellipticities (near circular) are reported. All specimens studied reflect both right- and left-handed polarized light. Depending on the species, two general types of polarization behaviour were observed. Chrysina macropus and Chrysina peruviana showed m41 values close to 0. Green stripes on Chrysina gloriosa showed similar polarization behaviour whereas gold stripes on the same beetle had much more pronounced m41 variations. Large m41 variations were also observed for Chrysina argenteola, Chrysina chrysargyrea and Chrysina resplendens. Four specimens of Chrysina resplendens show different m41 patterns suggesting differences in their structures.