US Patent 10459231 Augmented reality systems and methods with variable focus lens elements

An augmented reality display system includes a pair of variable focus lens elements that sandwich a waveguide stack. One of the lens elements is positioned between the waveguide stack and a user's eye to correct for refractive errors in the focusing of light projected from the waveguide stack to that eye. The lens elements may also be configured to provide appropriate optical power to place displayed virtual content on a desired depth plane. The other lens element is between the ambient environment and the waveguide stack, and is configured to provide optical power to compensate for aberrations in the transmission of ambient light through the waveguide stack and the lens element closest to the eye. In addition, an eye-tracking system monitors the vergence of the user's eyes and automatically and continuously adjusts the optical powers of the pair of lens elements based on the determined vergence of those eyes.