US Patent 10571636 Substrate-guide based optical systems with field curvature effect mitigation

A light-transmitting substrate has at least a first and a second major external surface. An electronic display source emanates light waves. A coupling-in optical arrangement couples light waves from the electronic display source into the light-transmitting substrate to effect total internal reflection of the coupled-in light waves between the major external surfaces of the light-transmitting substrate. An optical element is deployed in an optical path for light waves to traverse from the electronic display source into the light-transmitting substrate. The optical element defines a field curvature that causes light rays of the traversing light waves to diverge or converge. A lens is deployed in the optical path and reduces the field curvature. The electronic display source has a curvature that is matched to the reduced field curvature to counteract the divergence or convergence of the light rays caused by the reduced field curvature.