Full Mueller Matrix Characterization of Imaged Samples using Digital Holography

The Department of Defense relies on a worldwide network of radar and optical sites to maintain Space Situational Awareness.Although careful consideration during site selection process solves some of this mission's challenges, optical sensor imaging of objects at significant ranges is always hampered by many other factors, such as limited-aperture optics and atmospheric turbulence.There remains, however, a largely untapped wealth of information in the objects optical signature, in the form of the shape and material effects on the polarization of the reflected illumination light.These polarimetric effects can be described as diattenuation, retardance, and depolarization.These three characteristics for a given material can be fully expressed with a 4x4 element matrix known as the Mueller matrix.Previous polarimetric systems required tedious and time-consuming measurements to compute the Mueller matrix of materials over a large spectral and scattering angle range. Tau Technologies has developed an innovative approach based on digital holography to obtain the polarimetric measurements to accurately and rapidly determine the Mueller matrix.This novel approach can be used to create a detailed parametric Mueller matrix database which can be employed to precisely identify materials and their orientation on an unknown object that has been polarimetrically imaged at range.