Microsoft patents AR glasses that use light sensors to keep images aligned

1. A method for facilitating alignment control of image output, the method comprising: detecting an alignment image via an image sensor, the alignment image at least partially capturing an alignment marker depicted by a sampling portion of input light, the sampling portion of the input light being diffracted toward the image sensor by a sampling grating of a waveguide plate, the sampling portion of the input light being diffracted toward the sampling grating by an in-coupling grating of the waveguide plate, the in-coupling grating of the waveguide plate being configured to receive the input light from a projection system and (i) diffract a display portion of the input light toward an expansion grating of the waveguide plate for expansion and diffraction by the expansion grating toward an out-coupling grating of the waveguide plate for further expansion and diffraction by the out-coupling grating to generate an expanded-FOV representation of at least a portion of an image depicted by the input light for viewing by an eye of a user and (ii) diffract the sampling portion of the input light toward the sampling grating in a manner that causes the sampling portion of the input light to avoid diffraction by the expansion grating; detecting a second alignment image via a second image sensor, the second alignment image at least partially capturing a second alignment marker depicted by a second sampling portion of second input light, the second sampling portion of the second input light being diffracted toward the second image sensor by a second sampling grating of a second waveguide plate, the second sampling portion of the second input light being diffracted toward the second sampling grating by a second in-coupling grating of the second waveguide plate, the second in-coupling grating of the second waveguide plate being configured to receive the second input light from a second projection system and (i) diffract a second display portion of the second input light toward a second expansion grating of the second waveguide plate for expansion and diffraction by the second expansion grating toward a second out-coupling grating of the second waveguide plate for further expansion and diffraction by the second out-coupling grating to generate a second expanded-FOV representation of at least a portion of a second image depicted by the second input light for viewing by a second eye of the user and (ii) diffract the second sampling portion of the second input light toward the second sampling grating in a manner that causes the second sampling portion of the second input light to avoid diffraction by the second expansion grating; and modifying the image or the second image based upon the alignment image or the second alignment image or based upon a comparison of the alignment image and the second alignment image.