One-Dimensional Diffractive Waveguides for Unobtrusive Eye Tracking

The patent employs thin-film waveguide technology to replace bulky traditional display components. The waveguide is a thin transparent layer that guides light through total internal reflection, enabling compact headset design while maintaining optical performance. The thin-film structure eliminates the need for large optical elements, directly resolving the contradiction between component size and optical performance.

The patent replaces traditional mechanical optical systems with diffractive optical elements. Instead of using bulky lenses and mirrors for beam steering, the system uses diffractive gratings that manipulate light through diffraction effects. This substitution dramatically reduces component size while maintaining the ability to direct light to the user's eyes.

The patent creates a virtual image of the infrared emitter array using the waveguide and diffractive gratings. The real emitter array is positioned outside the field of view, but its light is coupled into the waveguide and redirected to create a virtual copy that appears to be located within the field of view. This copying approach allows the physical emitters to be hidden while maintaining accurate gaze tracking, as the camera captures reflections from the virtual emitter positions.

The waveguide acts as an intermediary between the physical emitter array and the user's field of view. It transports infrared light from emitters positioned outside the FOV to the eye box region, where it creates a virtual image. The diffractive output coupler serves as another intermediary, manipulating the light paths to achieve the desired virtual positioning. This intermediary approach resolves the contradiction by decoupling the physical location of emitters from their virtual optical position.