Single-pulse Mueller matrix polarimeter for rapid scene characterization LADAR

Abstract

We numerically and experimentally explore a new scanning LADAR architecture that enables Mueller matrix measurement for each point in a scene using a single ~10 ns illumination laser pulse. For the transmitter, we direct the laser pulse through an electro-optic crystal wherein a high-voltage ramp is synchronously applied. As the laser pulse propagates through the crystal the high-voltage ramp induces a time varying birefringence which results in a time varying polarization across the temporal envelope of the laser pulse. The receiver channel can be designed to measure the full Mueller matrix of the target by employing three polarization state analyzers or a subset of the Mueller matrix by employing fewer analyzers. This transmitter produces a well-defined temporal polarization variation which is used to illuminate the target. Knowing the temporal distribution of the transmitted polarization signal and using polarization analyzers in the receiver chain to measure the temporal distribution of the return signal’s polarization one can measure the entire Mueller matrix. We will introduce a model describing the transmitted and received signal polarization temporal distribution and show how the Mueller matrix can be extracted from this information. We will demonstrate the concept using a 10 ns, 1.06 μm laser pulse and a lithium tantalate electro-optic phase retarder in the transmitter and using two polarization analyzers in the receiver chain to measure a subset of the Mueller matrix in a point and shoot configuration. Measurements will be compared to theoretical reference to assess accuracy.