Analysis of infrared polarization signatures for backgrounds and objects

Recent investigations into the use of new electro-optical sensing modalities for the detection of landmines and other objects in complex backgrounds have led to the need to understand the optical properties of background materials (e.g., soils) in more detail. In particular, the use of polarimetric signatures in the optical and infrared domains has been the subject of much study; an understanding of soil optical properties and their variations is critical to evaluating the utility of these signatures. Our research examined polarimetric signatures and corresponding metrics in the context of a real world environment; specifically, we examined the spectral polarization characteristics of landmines and soils within a complex radiative environment. Our initial results indicate that the optical properties of sand dominate the resultant signature for the buried and flush-buried cases. Therefore, a spectral phenomenological model for the polarization signature of the combined sand-landmine system was developed for the infrared band (mid-wave and long-wave infrared) to study these issues in more detail; this model included the effects of various environmental factors such as solar insolation and atmosphere. The modeling paradigm centered on a radiative transfer approach coupled with heat transfer results to account for incident and emitted radiation simultaneously; the Hapke emission model served as a basis for the current investigations. This paper presents a description of the physics-based model for the spectral polarization signatures of buried, flush, and surface land mines and soil features along with signature effects arising from changes in the atmosphere and other environmental processes