Patent attributes
A head-mounted device may have projector, a first waveguide, a second waveguide, and an optical bridge sensor coupled between the first and second waveguides. An input coupler may couple light with a calibration pattern into the first waveguide. The calibration pattern may be included in visible or infrared light produced by the projector or may be included in infrared light produced by infrared emitters mounted to the first waveguide. An output coupler may couple the light having the calibration pattern out of the first waveguide. An additional output coupler may be used to couple visible light from the projector out of the waveguide and towards an eye box. An image sensor may generate image sensor data based on the light having the calibration pattern. Control circuitry may process the calibration pattern in the image sensor data to detect deformation or warping of the first waveguide.
