Eye tracking with switchable gratings

A near-eye display comprising:

• a projector for providing image light carrying an image in angular domain for viewing by an eye at an eyebox;
• a light source for providing illuminating light for illumination of the eye at the eyebox, wherein the illuminating light is invisible to the eye;
• and
• a switchable grating structure optically coupled to the light source for receiving and redirecting the illuminating light to a location of the eye at an eyebox.

A method for determining at least one of a position or orientation of an eye at an eyebox, the method comprising:

• providing illuminating light for illuminating the eye at the eyebox, wherein the illuminating light is invisible to the eye;
• using a switchable grating structure to redirect the illuminating light to a location of the eye at an eyebox;
• and
• using an eye tracking camera to obtain an image of the eye at the eyebox.