US Patent 11366298 Eye tracking based on telecentric polarization sensitive grating

A telecentric optical element that has a first surface, a second surface, and a layer of optically anisotropic material between the first surface and the second surface. The telecentric optical element is configured to receive light on the first surface, the light having propagated from a location within a predetermined distance range from the first surface of the optical element. The telecentric optical element is also configured to redirect a first portion of the light, having a first polarization, off the first surface of the telecentric optical element in an off-axis direction, and to transmit a second portion of light, having polarization different from the first polarization, to the second surface. An eye-tracking assembly that includes the telecentric optical element and a display device that includes the telecentric optical element are also disclosed.