Skew mirror auxiliary imaging

An electronic device comprising:

• a light source configured to output first light at a first wavelength greater than 700 nm;
• a waveguide configured to propagate the first light via total internal reflection;
• a medium layer on the waveguide;
• diffractive grating structures in the medium layer, the diffractive grating structures being configured to
• diffract the first light out of the waveguide, and
• diffract second light into the waveguide, the second light being at a second wavelength less than 700 nm;
• and
• a camera configured to receive the second light after diffraction by the diffractive grating structures.

An electronic device comprising:

• a projector configured to output first light at a first wavelength less than 700 nm;
• a waveguide having a first lateral surface and a second lateral surface opposite and parallel to the first lateral surface, the waveguide being configured to propagate the first light and the second light via total internal reflection between the first and second lateral surfaces;
• a medium layer having a third lateral surface and a fourth lateral surface opposite the third lateral surface, wherein the third lateral surface extends parallel to the first and second lateral surfaces and wherein the medium layer is layered onto the waveguide;
• diffractive grating structures in the medium layer, wherein
• the diffractive grating structures are configured to diffract the first light out of the waveguide and towards an eye box,
• the diffractive grating structures are configured to diffract, into the waveguide, second light incident upon the waveguide from the from the eye box,
• the second light is at a second wavelength greater than 700 nm,
• the waveguide is configured to propagate the first light via total internal reflection between the first and second lateral surfaces prior to diffraction by the diffractive grating structures, and
• the waveguide is configured to propagate the second light via total internal reflection between the first and second lateral surfaces after diffraction by the diffractive grating structures;
• and
• an image sensor, wherein the waveguide is configured to propagate the second light towards the image sensor and the image sensor is configured capture images of the second light.