US Patent 11073903 Immersed hot mirrors for imaging in eye tracking

Disclosed herein are techniques for imaging in eye tracking. An imaging system for eye tracking includes a camera configured to detect light in a first wavelength range, a substrate configured to be placed in front of an eye of a user, and at least one reflector located within the substrate. The at least one reflector is configured to receive light in the first wavelength range reflected by the eye of the user, reflect at least a portion of the received light in the first wavelength range to the camera, and transmit light in a second wavelength range different from the first wavelength range to the eye of the user. The substrate is transparent to both the light in the first wavelength range and the light in the second wavelength range.