Display alignment tracking in display systems

A device comprising:

• an alignment tracking waveguide;
• a first display module assembly (DMA) comprising a first light source and a first microelectromechanical system (MEMS) mirror configured to direct a first signal from the first light source to the alignment tracking waveguide;
• a second DMA comprising a second light source and a second MEMS mirror configured to direct a second signal from the second light source to the alignment tracking waveguide;
• a first photosensor configured to receive a first portion of the first signal via the alignment tracking waveguide;
• a second photosensor configured to receive a second portion of the second signal via the alignment tracking waveguide;
• and
• a controller configured to determine a first alignment indicator associated with the first portion of the first signal and a second alignment indicator associated with the second portion of the second signal.

A method in a device comprising a controller, a first light source, and a second light source, the method comprising:

• using a first microelectromechanical system (MEMS) mirror, scanning a first signal received from the first light source;
• using a first diffraction optical element (DOE) coupling the first signal to a first display waveguide to generate a first reflected signal;
• using a second DOE coupling the first reflected signal received via the first display waveguide to an alignment tracking waveguide;
• receiving by a first photosensor a first portion of the first reflected signal via the alignment tracking waveguide and using the controller determining a first alignment indicator associated with the first portion of the first reflected signal;
• using a second MEMS mirror, scanning a second signal received from the second light source;
• using a third DOE coupling the second signal to a second display waveguide to generate a second reflected signal;
• using a fourth DOE coupling the second reflected signal received via the second display waveguide to the alignment tracking waveguide;
• and
• receiving by a second photosensor a second portion of the second reflected signal via the alignment tracking waveguide and using the controller determining a second alignment indicator associated with the second portion of the second reflected signal.