Head-mounted display systems with gaze tracker alignment monitoring
A head-mounted device may have displays that provide images. Waveguides may be used in conveying the images to eye boxes. The waveguides may overlap lenses in a glasses frame or other head-mounted support structure. The waveguides and lenses may be transparent. This allows real-world objects to be viewed from the eye boxes. Infrared-light reflectors may overlap the lenses. Gaze tracking system light sources may supply infrared light that reflects from the infrared-light reflectors to the eye boxes to illuminate a user's eyes. Gaze tracking system cameras capture gaze tracking images of the eyes from the eye boxes to track the user's gaze. Fiducials associated with the infrared-light reflectors may be monitored using the gaze tracking system cameras. This allows components such as the gaze tracking system cameras to be calibrated.
1 . A head-mounted device, comprising:
a support structure;
a display coupled to the support structure and configured to produce a display image and to emit the display image in a first direction;
a waveguide coupled to the support structure and configured to receive the display image and to output the display image in a second direction that is opposite to the first direction;
a gaze tracker coupled to the support structure; and
a metal coating on the waveguide, wherein the metal coating is patterned to form a fiducial coupled to the waveguide, and wherein the gaze tracker is configured to capture an image of the fiducial in the first direction.
2 . The head-mounted device of claim 1 , further comprising:
a layer coupled to the waveguide, wherein the layer comprises a grating, and an additional fiducial is formed from the grating.
3 . The head-mounted device of claim 2 , wherein the grating is a surface grating on the layer.
4 . The head-mounted device of claim 2 , wherein the grating is embedded in the layer.
5 . The head-mounted device of claim 2 , wherein the waveguide has a first edge and an opposing second edge, and the layer extends from the first edge to the second edge.
6 . The head-mounted device of claim 1 , further comprising:
a layer coupled to the waveguide, wherein the metal coating is formed on the layer.
7 . The head-mounted device of claim 6 , wherein the waveguide has a first edge and an opposing second edge, and the layer extends from the first edge to the second edge.
8 . The head-mounted device of claim 1 , further comprising:
a layer coupled to the waveguide, wherein the layer comprises a stack of thin-film dielectric layers, and an additional fiducial is formed from a pattern in the layer.
9 . The head-mounted device of claim 8 , wherein the stack of the thin-film dielectric layers forms an infrared reflector.
10 . The head-mounted device of claim 8 , wherein the waveguide has a first edge and an opposing second edge, and the layer extends from the first edge to the second edge.
11 . The head-mounted device of claim 1 , wherein the metal coating is attached directly to the waveguide.
12 . The head-mounted device of claim 1 , wherein an additional fiducial is formed in the waveguide.
13 . The head-mounted device of claim 1 , further comprising:
a lens coupled to the waveguide, wherein the fiducial is formed in the lens.
14 . A head-mounted device, comprising:
a head-mounted frame;
a display in the head-mounted frame and configured to display an image;
a waveguide configured to receive the image;
a layer coupled to the waveguide, wherein the layer comprises a stack of thin-film dielectric layers;
a gaze tracking camera configured to gather respective gaze tracking images directly from an eye box without reflection; and
fiducials that overlap the waveguide, wherein the fiducials are formed from a pattern in the stack of thin-film dielectric layers, and the gaze tracking camera is configured to directly capture images of the fiducials without reflection.
15 . The head-mounted device of claim 14 , further comprising:
a lens that overlaps the waveguide; and
additional fiducials coupled to the lens.
16 . The head-mounted device of claim 15 , wherein the lens is a removable lens configured to be attached to the waveguide.
17 . A head-mounted device, comprising:
a head-mounted support structure;
a display system coupled to the head-mounted support structure and configured to produce a display image that is directed towards an eye box, wherein the display system comprises:
a display configured to produce the display image, and
a waveguide that includes an input coupler configured to couple the display image into the waveguide and an output coupler configured to couple the display image out of the waveguide, wherein the output coupler is selected from the group consisting of: a beam splitter, a prism, a holographic coupler, and a diffraction grating, and the waveguide further includes a fiducial formed on the output coupler; and
a gaze tracking system having a gaze tracking camera configured to capture an infrared gaze tracking image from the eye box while capturing an image of the fiducial.