US Patent 11238598 Estimation of absolute depth from polarization measurements

A head mounted display comprises an eye tracking system configured to enable eye tracking using polarization. The eye tracking system includes one or more illumination sources and an optical detector comprising polarization sensitive pixels. The one or more illumination sources are configured to illuminate a user's eye and generate reflections directed towards the optical detector. The eye tracking system determines, for each polarization sensitive pixel in a subset of the polarization sensitive pixels, one or more estimation parameters. The eye tracking system determines, for the subset of the polarization sensitive pixels, depth information for one or more glints associated with one or more surfaces of the eye, based in part on the polarization of the reflections and the one or more estimation parameters. The determined depth information is used to update a model of the eye. The eye tracking system determines eye tracking information based on the updated model.