Compact LiDAR Polarimetry via Time-Varying Transmit Polarization and an Elliptical Polarization Analyzer

摘要

In a recently developed compact LiDAR polarimeter, the transmit beam cycles through multiple polarization states withineach laser pulse and the receiver splits the received signal into multiple polarization state analyzers (PSAs), with the PSAoutputs temporally multiplexed into a single detector. This enables measurement of up to 12 of the 16 Mueller matrixelements of a target using limited hardware. However, due to numerical issues, one entire column of the matrix is notaccessible, including the M_(22) element (counting from zero) on the matrix diagonal. Experimental data show that for mostsurfaces of interest in a defense/security setting, the off-diagonal elements tend to be negligibly small and the diagonalelements vary between targets, so access to the diagonal elements is of high interest. In this paper, we show that if anelliptical PSA is used at the receiver and if most of the off-diagonal Mueller matrix elements are assumed to be zero apriori, then the otherwise inaccessible M_(22) element can be estimated. We explore the linear algebra of the problem todetermine the full list of which subsets of Mueller matrix elements can be estimated with this hardware configuration. Wealso theoretically and empirically investigate the effects of the rotations of the electro-optic transmitter plate and receiverelliptical PSA on the overall system performance.