Efficient eye illumination using reflection of structured light pattern for eye tracking

An eye-tracking unit for a near-eye display device, the eye-tracking unit comprising:

• a light source configured to emit a light beam in a first wavelength range;
• a beam splitter outside of a field of view of an eye of a user of the near-eye display device and configured to split the light beam in the first wavelength range and emitted by the light source into a plurality of light beams that forms a structured light pattern;
• a substrate configured to be placed in front of the eye of the user of the near-eye display device;
• a plurality of reflectors within the substrate and configured to receive the plurality of light beams from the beam splitter;
• and
• a camera configured to detect light in the first wavelength range, wherein each of the plurality of reflectors is configured to:
• intercept one or more light beams from the plurality of light beams;
• reflect light in the one or more light beams from the plurality of light beams to the eye of the user;
• and
• transmit light in a second wavelength range from a display panel of the near-eye display device to the eye of the user;
• wherein the substrate is transparent to both light in the first wavelength range and light in the second wavelength range;
• and wherein the camera is configured to receive light in the first wavelength range and reflected by the eye of the user to form an image frame for eye-tracking,
• wherein each reflector of the plurality of reflectors comprises a reflecting surface;
• and
• wherein a shape or a curvature of the reflecting surface of each reflector of the plurality of reflectors is configured such that a virtual image of the light source formed by the reflecting surface of each reflector of the plurality of reflectors is at a different location in front of the eye of the user.

A method of tracking an eye of a user of a near-eye display device, the method comprising:

• illuminating, by a light beam in a first wavelength range emitted from a light source, a beam splitter outside a field of view of the eye of the user;
• splitting, by the beam splitter, the light beam in the first wavelength range and emitted by the light source into a plurality of light beams propagating toward a substrate of the near-eye display device, the plurality of light beams forming a structured light pattern, the substrate located in front of the eye of the user;
• intercepting, by a plurality of reflectors embedded in the substrate and configured to receive the plurality of light beams from the beam splitter, the plurality of light beams;
• reflecting, by the plurality of reflectors, the plurality of light beams to the eye of the user;
• and transmitting light in a second wavelength range from a display panel of the near-eye display device through the substrate and the plurality of reflectors and to the eye of the user;
• wherein each reflector of the plurality of reflectors comprises a reflecting surface;
• and
• wherein a shape or a curvature of the reflecting surface of each reflector of the plurality of reflectors is configured such that a virtual image of the light source formed by the reflecting surface of each reflector of the plurality of reflectors is at a different location in front of the eye of the user.