Polarization imaging: principles and integrated polarimeters

Polarization is a general descriptor of light and contains information about reflecting objects that traditional intensity-based sensors ignore. Difficult computer vision tasks such as image segmentation and object orientation are made tractable with polarization vision techniques. Specularities, occluding contours, and material properties can be readily extracted if the Stokes polarization parameters are available. Astrophysicists employ polarization information to measure the spatial distribution of magnetic fields on the surface of the Sun. In the medical field, analysis of the polarization allows the diagnose of disease in the eyes. The retinae of most insect and certain vertebrate species are sensitive to polarization in their environment, but humans are blind to this property of light. Biologists use polarimeters to investigate behaviors of animals-vis-a-vis polarization-in their natural habitats. In this paper, we first present the basics of polarization sensing and then discuss integrated polarization imaging sensors developed in our laboratory.