Adding polarimetric capabilities to a remote sensing system provides more information about the scene than would be available from a system without polarization sensitivity. One example is scene characterization with Mueller matrices, which can be measured by an active polarimeter, consisting of a polarization state generator and a polarization state analyzer. Incoherent lidars have been built around this concept, often using a bistatic configuration with a polarization state generator in the transmitted beam path and an independent polarization state analyzer in the received beam path. Coherent lidars have yet to make significant use of polarimetric information owing to the more complicated lidar architecture. Here we present a simple monostatic coherent (frequency-modulated continuous-wave) lidar with potential capability of measuring ten of the sixteen Mueller matrix coefficients. This is made possible through the use of two liquid crystal variable retarders acting as both the polarization state generator and polarization state analyzer. This paper describes the design and calibration of this instrument with preliminary measurements.
